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PROGRESSIVE  SERIES  VOLUME  I 

PRACTICAL  MANUAL  OF 
DENTAL  CASTING 


BEING  THE 
RECORDED    EXPERIENCES    OF 
MANY  ABLE  AND  EMINENT  MEN 
IN   THE   DENTAL   PROFESSION 


Profusely  Illustrated 


Reprinted  from  THE  DENTAL  SUMMARY,   1909-1913 


SECOND  EDITION 
REVISED  AND  ENLARGED 


Published  by 

THE  RANSOM  &  RANDOLPH  CO. 

Toledo,  Ohio 

1913 


m^^ 
^^t 
\(^i^ 


Copyright,  1913 

BY 

The  Ransom  &  Randolph  Co. 


Printed  by 

The  Express  Publishing  and  Printing  Co. 

Toledo,  Ohio 

1913 


»»< 


PREFACE 


IN  PREPARING  THIS  BOOK  and  offering  it  to  the  dental 
profession,  the  sole  object  has  been  to  place  within  easy  and 
convenient  access,  in  concise,  permanent  form,  the  best 
thoughts  of  the  most  expert  and  successful  casting  men,  together 
with  records  of  their  results,  as  they  have  been  expressed  through 
the  pages  of  The  Dental  Summary  during  the  past  three  years. 

To  this  has  been  added  historical  articles,  covering  the 
origin  and  progress  of  the  casting  art  as  applied  to  dentistry, 
showing,  step  by  step,  the  really  wonderful  advancement  that 
has  been  made  and  the  immense  usefulness  of  that  art  to  the 
dental  profession. 

The  book  will  be  found  in  line  with  mocern  methods.  Every 
phase  of  the  casting  process  has  been  touched  upon,  some  of 
them  worked  out  exhaustively;  and,  in  its  pages,  will  be  found 
much  practical  advice  and  instruction  that  cannot  fail  to  be  help- 
ful to  all,  while,  for  the  beginner,  it  would  seem  to  be  altogether 
invaluable. 

The  idea  of  profit  has  not  been  considered  by  the  publishers. 
The  price  at  which  the  book  is  offered  ought  to  convince  even,'- 
one  of  that  fact.  The  preservation  of  the  knowledge  contained 
therein  and  the  placing  of  that  knowledge  in  the  hands  of  the 
profession  has  seemed  a  sufficiently  high  ideal  of  service  to  warrant 
the  labor  and  expense  involved. 

The  Publishers. 


PRACTICAL  MANUAL 
OF  DENTAL  CASTING 


ANCIENT  ORIGIN  OF  DENTAL  CASTING 

By  L.  W.   Strycker,   New   York. 

The  object  in  preparing  this  article  is  not  to  change  public  opinion  nor  to  bring 
discredit  upon  anyone.  Rather  is  it  to  enlighten  the  dental  public  upon  a  subject  con- 
cerning which  much  erroneous  information  is  extant,  in  the  hope  that  others  may 
take  up  the  subject  and  work  it  out  for  the  benefit  of  all,  as  did  the  Old  Masters  in 
an  age  when  time  was  nothing  and  art  everything. 

The  facts  herein  laid  before  the  public  have  been  gained  by  the  study  of  old 
text-books  as  well  as  from  the  references  to  current  authorities  that  are  given. 
Being  in  possession  of  this  knowledge,  the  writer  looks  upon  it  as  his  duty  to  give  it 
out.  By  withholding  it,  he  would  lay  himself  open  to  the  charge  of  secretiveness, 
and  bring  dishonor  upon  himself  in  later  years. 

Of  course,  only  the  most  brief  outline  can  be  given  in  such  an  article.  Any  at- 
tempt to  print  all  of  the  valuable  information  that  has  been  gained  by  this  investiga- 
tion would  be  entirely  out  of  the  question,  as  volumes  would  be  required  to  reproduce 
it.  The  books  themselves  should  be  read  by  every  man  who  is  interested  in  the 
subject  sufficiently  to  take  the  time  necessary.  For  those  who  have  not  the  time 
at  their  disposal,  this  brief  resume  has  been  prepared,  and  is  here  offered  for  what  it 
may  be  worth  to  the  profession. 


Fig.  1 — "  Malaga  a  la  Francaise,"  or 
piece  casting.  The  model  com- 
pleted. 


Fig.    2 — Piece    casting;    the    model 
"inverted." 


The  most  cursory  investigation  of  the  authorities  given  will  convince  any  man 
that  casting  by  the  so-called  "modern"  processes  is  by  no  means  new;  that  it  is 
simply  a  neglected  and  almost  forgotten  art.  In  taking  up  the  subject  we  must  go 
hack  to  the  most  ancient  text-books  and  records,  the  older  the  better.  The  methods 
that  we  are  now  so  eager  to  learn  arc  handled  by  the  Old  Masters  in  the  founding  art 
with  most  satisfactory  clearness  and  particularit\-  of  detail.  Kspeciall\'  is  this  true 
of  the  "Cire  Perdue"  or  disappearing  model  or  "wasting  wax"  proc-ess,  which  was 
known  and  in  common  use  almost  countless  ages  ago. 


6  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

This  also  is  true  of  two  of  the  methods  for  forcing  the  metal  into  the  mold  in 
common  use  today — centrifugal  force  and  pressure.  The  centrifugal  method  is 
first  mentioned  in  the  old  books,  and  we  reproduce  an  illustration  of  one  of  these 
ancient  centrifugal  casting  machines  (Fig.  4).  This  was  used  for  casting  bronze 
busts  and  other  objects  of  art. 

Later  the  mechanical  pressure  air-pressure  machines  were  invented  and  became 
well  known.     Illustrations  are  given  of  these  ancient  devices  (Figs.  5  and  7). 

The  earliest  account  of  the  casting  of  bronze  by  the  cire  perdue  or  disappearing 
wax  model  process  is  given  in  Knight's  American  Mechanical  Dictionary  as  22.30  B.  C, 
and  has  to  do  with  a  reference  by  Herodotus  and  Diodorus  to  massive  bronze  statues 
that  were  set  up  in  the  Temple  of  Belus,  in  Babylon. 


Fig.  3 — "Cire  Perdue,"  or  Waste- 
Wax  Method.  Identical  with 
Modern  Disappearing  Model 
Methods. 


Fig.  4    -Ancient  Centrifugal  Casting 
Machine.     Date  unknown. 


In  Isaiah,  xliv,  12,  written  about  712  B.  C,  is  an  account  of  the  making  of  the 
golden  calf  by  Aaron,  supposed  to  be  several  centuries  earlier,  or  about  1491  B.  C. 
"He,"  Aaron,  "received  then  the  golden  ear-rings  of  the  people  at  their  hands,  and 
fashioned  it  with  a  graving  tool,  after  he  had  made  of  it  a  moulten  calf." 

The  Colossus  set  up  by  Nero  the  Roman  emperor,  before  his  golden  house, 
near  the  site  of  the  Temple  of  Venus  at  Rome,  was  a  bronze  figure  of  himself,  the  work 
of  Zenodorus.  This  was  also  cast  by  the  cire  perdue,  or  disappearing  wax  model 
process. — Knight's  American  Mechanical  Dictionary. 

Myer's  Ancient  History  tells  us  that  bronze  was  cast  by  the  Greeks  about  the 
eighth  century  B.  C,  which  also  speaks  of  Lycippus  as  being  renowned  for  his  works 
in  bronze. 

This  knowledge,  that  the  ancients  were  in  possession  of  the  greatest  skill  in  the 
art  of  casting  metals,  lets  a  flood  of  light  in  upon  some  of  their  most  famous  produc- 
tions now  preserved  in  museums.  Until  this  was  learned  concerning  them,  the 
wonder  was  how  such  marvelous  reproductions  could  have  been  made  with  the 
crude  methods  supposed  to  be  at  their  command.  The  use  of  the  disappearing 
wax  model,  invested  and  cast  upon  a  large  scale,  it  is  true,  but  in  precisely  the  same 
manner  as  that  now  employed  in  dentistry,  makes  all  that  clear. 

"The  great  bronze  lions  of  the  Nelson  Monument  in  London  are  a  sad  example 
of  the  present  low  state  of  the  founder's  art.  Coarse  sand  casting  in  England  now 
takes  the  place  of  the  delicate  cire  perdue  process." — Encyclopedia  Brittannica, 
Vol.  14,  page  79. 


Ancient  origin  of  dental  casting  7 

The  full-length  recumbent  effigies  of  Henry  III  and  Queen  Eleanor  at  West- 
minster, cast  in  bronze  by  this  process  (disappearing  wax  model  method)  are  equal, 
if  not  superior,  in  artistic  beauty  to  any  sculptor's  work  of  the  same  period."  (End 
of  the  thirteenth  century.) — Encyclopedia  Britlannica,  Vol.  14,  page  77. 

"The  great  candelabrum  in  Seville  cathedral  is  the  finest  specimen  of  sixteenth 
century  metal  work  in  Spain.  It  is  mainly  the  work  of  Bart  Morel,  in  1562.  It  is 
cast  in  bronze,  enriched  with  delicate  scroll-work,  foliage  and  numbers  of  well- 
modeled  statuettes,  cast  by  the  disappearing  wax  model  method." — Encyclopedia 
Britlannica,  Vol.   14,  page  76. 

"In  Work-Shop  Receipts,"  published  by  E.  Spon,  London,  page  221,  is  de- 
cribed  the  two  methods  of  wasted-wax  casting:  'Malaga  a  la  Francaise,'  or  piece 
casting.  (See  Figs.  1  and  2.)  The  other  process  is  that  known  as  cire  perdue,  or 
waste-wax  pattern.  It  is  the  more  ancient  of  the  two  and  has  been  practiced  from 
time  immemorial  by  the  artists  and  artizans  of  Italy."     (See  Fig.  3.) 

"The  mention  of  molds  for  the  casting  of  wax  figures  is  ascribed  to  Lysistratus. 
about  328,  B.  C." — Knight's  American  Mechanical  Dictionary,  Vol.  2,  p.  1459. 

"Suppose  a  small  ornamented  vase  were  to  surmount  the  pillar;  the  founder 
would  prepare  the  pattern  for  this  in  a  more  elaborate  manner.  He  would  first 
mold  it  in  wax." — Chambers'  Encyclopedia,  Wo\.  4.,  p.  454.     Published  1870. 

"An  old  method  which  is  still  employed  in  Italy  is  to  make  a  core  composed  of 
potter's  clay,  brick  dust,  cow's  hair  or  some  other  composition,  and  over  this  to  model 
the  figure  in  wax;  then  the  other  mold  is  formed  on  this  of  some  composition  of 
which  loam  is  the  principal  part.  The  whole  is  then  dried,  and  baked,  in  an  oven, 
until  the  wax  is  melted  and  cleaned,  and  the  mold  is  rendered  sufficiently  porous." — 
Amn.  Cyclopedia,  \o\.  4,  p.  85.      Published  1S75.      (The  italics  are  mine.) 


Fig.  5 — Pressure  Casting  Machine, 
about  1819. 


Fig.    6 — Type     Casting     Macliine. 
Casts  by  pressure. 


"Castings  of  great  delicacy  are  produced  by  using  models  of  wax.  These  are 
embedded  in  molds  of  finely-ground  earth,  which  are  then  heated  red  hot.  The  mold 
is  baked  and  the  wax  disappe.a.rs;  and  the  metal,  when  poured,  exactly  takes  its 
V\2ice."— Knight's  Amn.  Mech.  Diet.,  \'ol.  1.     Published  1880. 

The  most  clearly  written  directions  for  using  the  disappearing  wax  model 
method  are  given  on  page  72,  \o\.  14,  Enc.  Brit.,  published  in  1891,  h\  R.  S.  Peale 
Co.,  Chicago.  These  directions  were  reproduced  almost  word  for  word,  sufficiently 
so  to  warrant  the  assertion  that  they  are  identical,  in  the  first  directions  given  to  us 
for  the  casting  of  inlays  and  the  like;  particularh-  where  we  are  told  to  "use  an  in- 
vestment mixed  with  water  to  the  consistency  of  cream,  and  apply  with  a  brush, 
until  a  coating  is  formed  over  the  wax,"  etc.     Here  is  the  quotation: 


8  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

"methods  ok  manipulation  in  metal  work. 

"Gold,  silver  and  bronze  may  be  treated  in  various  ways,  the  chief  of  which 
are  (I)  casting  in  a  mold,  (2)  treatment  by  hammering  and  punching  (swaging; 
French  repousse).  The  first  of  these,  casting,  is  chiefiy  adapted  for  bronze,  or  in 
the  case  of  more  precious  metals,  only  if  they  are  used  on  a  very  small  scale.  The 
reason  for  this  is  that  a  repousse  relief  is  of  much  thinner  substance  than  if  the  same 
design  were  cast,  even  by  the  most  skilful  metal  worker,  and  so  a  large  surface  may 
be  produced  with  a  very  small  expenditure  of  valuable  metal. 

"Casting  is  probably  the  most  primitive  method  of  metal  work.  This  method 
has  passed  through  three  stages,  the  first  being  represented  by  solid  castings,  such  as 
are  most  celts  and  other  implements  of  prehistoric  times;  the  mold  was  formed  in 
clay  or  stone,  and  the  fluid  metal  was  poured  in  until  the  hollow  was  full.  The  next 
stage  was,  in  the  case  of  bronze,  to  introduce  an  iron  core,  probably  to  save  needless 
expenditure  of  the  more  valuable  metal.  The  British  Museum  possesses  an  inter- 
esting Etruscan  or  archaic  Italian  example  of  this  primitive  device.  It  is  a  bronze 
statuette  from  Sessa,  on  the  Volturus  River,  about  two  feet  high,  of  a  female,  stand- 
ing, robed  in  a  close-fitting  chiton.     The  presence  of  the  iron  core  has  been  made 


Fig.  7 — Dr.   Carroll's  Air  Pressure 

Casting  Machine,   188.5-6.  , 

visible  by  the  splitting  of  the  figure,  owing  to  the  unequal  contraction  of  the  two 
metals. 

"The  third  or  last  stage  in  the  progress  of  the  art  of  casting  was  the  employment 
of  a  core,  generally  of  clay,  around  which  the  metal  was  cast  in  a  mere  skin,  only 
thick  enough  for  strength,  without  waste  of  metal. 

"The  Greeks  and  Romans  attained  to  the  greatest  po.ssible  skill  in  tliis  process. 
Their  exact  method  is  not  certainly  known,  but  it  appears  probable  that  they  were 
acquainted  with  the  process  now  called  cire  perdue  (wasting  wax  method),  the  same 
as  that  employed  by  the  great  Italian  artists  in  bronze,  and  still  unimproved  upon, 
even  at  the  present  day.  Cellina,  the  great  Florentine  artist  of  the  sixteenth  century, 
has  described  it  fully  in  his  Trattalo  delta  Scultura.  If  a  statue  were  to  be  cast,  the 
figure  was  first  roughly  modeled  in  clay,  only  rather  smaller  in  dimensions  than  the 
future  bronze;  all  over  this  a  skin  of  wax  was  laid  and  worked  by  the  sculptor's 
modeling  tools  to  the  required  form  and  finish.  A  mixture  of  pounded  brick,  clay 
and  ashes  was  then  ground  finely  in  water,  to  the  consistency  of  cream;  and 
successive  coats  of  this  mixture  were  then  applied  -ivilh  a  brush,  imtil  a  second  skin 
was  formed  all  over  (he  wax,  fitting  closely  into  every  line  and  depression  of  the 
modeling.  Soft  clay  was  then  carefully  laid  on  to  strengthen  the  mold,  in  con- 
siderable thickness,  till  the  whole  statue  ajjpeared  like  a  shapeless  mass  of  clay, 
around  which  iron  hoops  or  rings  were  bound  to  hold  it  all  together. 


ANCIENT  ORIGIN  OF  DENTAL  CASTING  9 

"  THl'  whole  was  iheii  tlioroui^lil}'  drifl  and  placed  in  a  liol  own,  which  baked 
the  clay,  both  of  the  core  anrl  the  outside  nujld,  and  mki.TEI)  THE  wax,  which  was 
allowed  to  run  oLit  through  small  holes  made  for  the  |Hiri)ose.  The  mold  was  now 
ready  for  casting,"  etc. 

So  here  we  have  a  fairly  accurate  and  connected  history  of  the  disappearing 
MODEL  procp:ss,  and  will  next  take  up  casting  machines  in  the  use  of  which  pres- 
sure was  employed. 

Our  cut,  Fig.  4,  shows  a  primiti\e  centrifugal  machine,  used  for  casting  a  bust. 

Knight's  Amn.  Mech.  Diet.,  Vol.  1,  published  1880,  says:  "In  the  English 
patent,  No.  3197,  January  28,  1809,  the  molds  for  casting  are  upright  and  are  made 
to  revolve  on  pivots  or  spindles.  The  centrifugal  force  causes  the  metal  to  fill  up 
all  parts  of  the  mold."  It  also  says:  "  In  an  American  patent  of  1857  the  car  wheels 
are  revolved  (while  being  cast)  so  that  the  first  metal  poured  is  made  to  forrn  the 
tread  of  the  wheel,  and  the  second  portion  to  form  the  body  of  the  wheel,"  and  further: 
"In  Bessemer's  patent  the  metal  is  poured  into  fast-revolving  cjdinders,  the  rapid 
rotation  of  which  causes  the  metal  to  collect  on  the  inside  of  same,  when  it  is  allowed 
to  cool.     It  is  then  split  open  and  rolled." 

The  same  volume  then  speaks  cf  pressure  casting  machines.  "To  obtain  the 
best  results  in  compact  metal  castings,  destitute  of  porcsity,  and  with  sharp  defini- 
tion on  the  angles  and  ornaments,  casting  under  pressure  has  been  devised.  See 
Hollingrake's  English  patent,  1819." 

Following  this  it  gives  a  drawing  of  the  machine,  which  we  ha\"e  reproduced  as 
Fig.  5.     Going  farther,  it  says: 

"In  one  case  the  molds  are  so  arranged  that  the  top  part  serves  as  the  follower 
of  a  press,  and  is  operated  on  by  screws.  The  top  part  tits  closely  into  the  matrix 
and  is  provided  with  ingates  for  the  metal,  which  are  closed  by  slides  when  the  mold 
is  full.  The  pressure  is  applied  to  the  metal  while  in  a  melted  state,  with  sufficient 
force  to  expel  the  air  and  gas  from  and  solidify  the  metal.'' 

Then  it  speaks  of  Smith's  process  of  compression  casting.  The  face  of  the  article 
is  covered  with  a  preparation  of  potter's  clay,  the  model  is  withdrawn  by  a  little 
india-rubber  suction  apparatus,  "and  we  have  an  exact  fac-simile,  ready,  when  dried, 
to  be  cast  from.  Nothing  can  exceed  the  beauty  of  the  result  by  casting  the  metal 
under  pressure  in  the  mold.  Thus  prepared,  screws  and  nuts  which  never  had  a 
tool  put  on  them,  lea\e  nothing  to  be  desired  in  the  way  of  accuracy-  and  com- 
pleteness." 

On  page  604,  describing  the  term  "compression-casting,"  we  find  this:  "A 
mode  of  casting  bronzes,  etc.,  in  molds  of  potter's  clay,  under  a  pressure  which  causes 
the  metal  to  flow  into  the  delicate  tracery  left  by  the  pattern.  This  work  nearly 
approaches  the  work  of  the  graver  and  chisel.  It  is  especially  used  in  casting  house- 
builders'  hardware,  letters,  numbers  for  houses,  etc." 

In  Vol.  2,  page  1462,  is  the  following:  "Soft  and  perishable  objects -may  be 
so  molded  as  to  produce  a  single  casting  by  one  of  the  several  following  methods, 
which  are  adapted  to  the  procuring  cf  castings  cf  small  animals,  insects,  flowers, 
feathers,  ferns,  sea- weed,  wax  models,  etc: 

1.  Support  the  tibject  in  the  center  of  a  small  iio\,  by  needles;  one  or  two 
should  be  sufficientK'  largi'  to  form  ingates.  l-'ine  ri\ir  mud  is  dropped  into  the  box 
and  shaken  around  so  as  to  adheri'  to  tin-  object.  When  partialK'  dr\-,  a  coarser 
grade  of  silt  is  thrown  in  until  the  box  is  filled.     The  needles  and  ingate  wires  are 


10  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

withdrawn,  the  meld  burned  to  reduce  the  object  to  ashes,  which  are  shaken  or 
blown  out,  when  the  mold  is  ready  for  casting. 

2.  Another  method  is  to  take  the  object  itself  or  a  wax  model,  such  as  that  of  a 
flower,  and  suspend  it  in  a  box  while  plaster  of  Paris  is  carefully  poured  around  it. 
The  application  of  heat  causes  the  object  to  burn  or  the  plaster  to  absorb  the  wax; 
or,  if  the  latter  be  in  excess,  it  may  be  poured  out.  The  strings  by  which  the  object 
was  suspended  are  withdrawn  and  the  mold  is  ready  for  casting.  This  plan  was 
adopted  in  casting  the  feather  of  the  equestrian  statue  of  George  III,  at  Pall  Mall, 
London;  and  specimens  of  ears  of  wheat,  flashy  flowers,  such  as  coxcomb,  and  other 
beautiful  objects." 

We  are  indebted  to  the  Italians  and  French  of  the  fifteenth,  sixteenth  and  seven- 
teenth centuries  for  safe  molds;  the  ones  mentioned  above  are  termed  waste  molds. 

On  page  2312,  Vol.  3,  this  work  describes  the  casting  of  busts  and  statuary.  The 
print  is  very  fine  and  the  article  would  fill  a  single  issue  of  anj'  of  our  dental  journals. 
The  article  was  written  in  1844.     The  description  in  part  follows: 

"The  present  system  of  statuary  casting  is  as  follows: 

1.  Take  a  cast  in  plaster  sections,  which  together  form  a  matrix. 

2.  Cover  the  inside  of  these  sections  with  a  shell  of  wax. 

3.  Place  the  sections  together  so  as  to  form  a  mold. 

4.  Fill  the  inside  with  cla^'  or  slush,  so  as  to  form  a  core  with  supports  to  sus- 
tain it  independently  of  the  mantle. 

5.  Remove  the  plaster  sections,  the  wax  adhering  to  the  clay. 

6.  Work  up  the  wax  surface  into  complete  form  by  hand. 

7.  Coat  with  porous  clay  composition  to  form  mantle. 

8.  Bake  in  a  furnace,  melting  or  burning  out  the  wax. 

9.  Run  the  metal  into  the  baked  clay  mold. 

The  church  of  St.  Isaac  at  St.  Petersburg  is  decorated  with  a  large  number  of 
statues  and  figures  in  relief  obtained  by  this  process." 

On  pages  2674-2675,  Vol.3,  the  type-casting  machine  is  described,  showing  the 
Bruce  machine,  and  says  that  in  1850  a  French  invention  by  M.  Didot  was  designed 
to  cast  about  200  types  at  once,  requiring  about  twenty  seconds.  Pressure  brought 
to  bear  upon  the  mclten  metal  forced  it  into  all  the  recesses  of  the  molds. 

Westcott's  machine,  U.  S.  patents  115,  796,  June  6,  1871;  169215  and  169216, 
October  25,  1875,  casts  and  sets  the  type  by  pressure  on  the  molten  metal. 

In  the  American  Cyclopedia,  Vol.  13,  p.  791,  published  1875,  we  find  the  follow- 
ing: "There  are  difficulties  in  making  large,  thin  vases,  which  have  been  overcome 
at  Sevres  by  the  employment  of  atmospheric  pressure  and  exhaustion.  A  plaster 
mold  is  used,  and  the  cast  is  made  either  by  covering  the  mouth  of  the  mold  and  forc- 
ing air  into  the  interior,  or  by  exhausting  the  air  through  the  porous  plaster  by  means 
of  an  exterior  air-tight  case." 

The  Century  Dictionary  and  Cyclopedia,  Vol.  1,  p.  849,  published  1889,  in  de- 
scribing the  meaning  of  the  words  "Compression  Casting,"  uses  these  words:  "A 
method  of  casting  in  molds  of  potter's  clay,  with  sufficient  pressure  to  force  the  metal 
into  the  most  delicate  tracery  left  by  the  pattern.  It  is  used  in  casting  letters, 
stamps,  house  numbers,  house  builders'  hardware,  etc."  Further  on  it  defines  the 
meaning  of  the  words  "Casting  Press"  as  "a  press  in  which  metal  is  cast  under 
pressure." 

Chambers'  Encyclopedia,  Vol.  9,  p.  606,  published  1870,  says  that  various  at- 
tempts were  made  during  the  early  part  of  the  century  to  cast  type  by  machinery, 


ANCIENT  ORIGIN  OF  DENTAL  CASTING  11 

but  that  the  first  successful  type-casting  machine  was  invented  h\   David   Bruce. 
Jr.,  of  New  York,  and  patented  March  17,  1838. 

The  first  type-casting  machine  was  patented  in  the  United  States  in  1828  by 
William  M.  Johnson,  but  it  did  not  produce  good  types.  The  patent  was  sold  to 
George  Bruce,  and  the  machine  was  used  by  him  until  1845.  David  Bruce  mean- 
while patented  another  machine,  1843,  with  improvements  two  years  later,  which 
gave  entire  satisfaction  and  is  now  in  general  use  in  American  type  foundries. 

This  same  volume  gives  an  illustration  of  a  type-casting  machine,  and  describes 
it  as  follows: 

"A  type-casting  machine  consists  first  of  a  small  melting-pot,  which  contains 
the  molten  metal.  In  the  interior  of  the  pot  is  arranged  a  forcing  pump  and  a 
valve  for  admitting  the  metal  under  the  piston,  and  also  for  preventing  of  the  return 
of  the  metal  into  the  mass  in  the  pot  when  the  piston  is  depressed,  and  thus  securing 
the  full  force  exerted  upon  the  piston  being  transmitted  by  the  piston  to  the  molten 
metal  under  it,  and  forcing  it  through  a  narrow  channel  to  the  mould,"  etc. 

The  Century  Dictionary,  Vol.  3,  p.  2531,  in  describing  pressed  glass,  says:  "Glass 
while  in  a  molten  state,  is  brought  to  shape  in  a  mold  by  a  plunger." 

The  Encyclopedia  Brittannica,  9th  edition.  Vol.  18,  p.  481,  describes  a  method 
of  casting  steel  ingots  employed  by  Sir  Joseph  Whitworth,  by  applying  hydraulic 
pressure  to  the  metal  in  the  mold  until  it  solidifies,  which  "has  been  adopted  by  the 
inventor  with  great  success  in  the  prevention  of  blow-holes  and  similar  imper- 
fections." 

Now,  let  us  see  what  all  this  has  to  do  with  dentistry.  (See  Fig.  7.)  This 
illustration  shows  a  machine  devised  by  Dr.  C.  C.  Carroll,  cf  Meadville,  Pa.,  in 
1885  or  '86,  for  casting  plates  by  the  pressure  process.  Dr.  Carroll  turned  o\er  his 
invention  unreservedly  to  the  profession,  the  following  paragraph  appearing  in  the 
copy  of  Directions  given  with  the  machine: 

"These  goods  are  placed  before  the  profession  on  their  merits,  upon  the  most 
liberal  terms,  without  any  charge  of  license  or  royalty  upon  the  patents  by  which 
they  are  covered,  and  by  the  use  of  which  all  other  patents  for  crowns,  bridges,  etc., 
are  evaded." 

He  also  gives  full  directions  for  casting,  and  says:  "Maintain  the  pressure 
about  five  seconds  to  give  the  molecules  of  metal  time  to  arrange  themselves  under 
pressure.     Otherwise  there  may  be  small  pits  over  the  surface  of  the  denture." 

He  further  says:  "Mold  upon  the  teeth  in  thin  paraffine  wax  the  crown  or 
bridge  that  is  intended  to  be  worn,"  etc.  It  seems  fair  to  assume  that  he  made  his 
abutments  and  no  doubt  his  inlays  in  the  same  manner. 

Now,  let  us  turn  to  periodical  literature  on  the  subject: 

In  the  account  of  the  meeting  cf  the  First  District  Dental  Society,  State  of  New 
York,  Tuesday  evening,  March  13th,  1894,  at  the  New  York  Academy  of  Medicine, 
published  in  the  Dental  Cosmos,  Vol.  36,  No.  5,  May,  1894,  appears  the  following: 

"Dr.  George  F.  Reese,  of  Brooklyn,  N.  Y.,  demonstrated  the  method  of  adjust- 
ing his  gold  alloy  cast  crown: 

"A  right  superior  lateral  root  was  selected  in  a  lady  patient.  He  had  the  root 
already  prepared;  then  the  artificial  crown,  which  was  a  plain  rubber  tooth,  was 
ground  to  fit  to  the  root  and  gum;  next  a  piece  of  placinum  wire,  coated  with  gold 
the  length  cf  the  rcot,  was  hammered  flat  at  the  exposed  end  and  bent  into  a  foot 
shape.  It  was  then  fastened  by  wax  to  the  artificial  crown  and  an  impression  of 
the  root  was  taken.     This  was  put  in  and  remo\'ed  a  number  of  times,  the  surplus 


12  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

taken  off  with  a  heated  spatula  until  adaptation  and  contour  were  correctly  ob- 
tained, down  to  the  finest  detail.  It  was  then  placed  in  cold  water  to  harden  the 
wax  and  tried  in  again.  Everything  being  found  satisfactor}',  two  points  of  wax  were 
put  on  the  back  of  the  crown,  which  was  then  invested  in  plaster  of  Paris.  After 
hardening  the  wax  was  grooved  out,  the  matrix  heated,  and  the  wax  melted  out  by  a 
fine  stream  of  boiling  water.  Two  pockets  were  then  made,  one  being  the  pouring, 
the  other  the  vent  gate.  This  was  again  invested  in  plaster,  which  was  now  ready 
after  hardening  and  standing  a  couple  of  hours  to  be  put  in  the  drying  oven.  When 
dry,  which  is  shown  by  the  mirror  test,  the  gold  alloy  was  melted  and  heated  until 
it  turned  a  purplish  tint,  when  it  was  ready  to  cast. 

"The  doctor,  after  finishing,  proceeded  to  insert  a  duplicate  crown.  By  so 
doing  it  was  shown  that  the  crown  fitted  perfectly.  He  then  permanently  fastened 
it  by  drying  out  the  root  and  coating  the  crown  root  with  oxyphosphate  cement." 

Page  269  of  the  April,  1889,  Dental  Cosmos,  shows  us  the  following:  "Dr. 
Reiss,  of  Brooklyn,  showed  a  specimen  of  an  improved  porcelain  crown." 

Page  293,  same  number:  "Dr.  J.  N.  Crouse,  by  permission,  called  attention 
to  the  Dental  Protective  Association.  He  said  that  it  was  necessary  to  act  at  once, 
as  they  must  have  money  now  to  carry  on  the  fight  against  The  Tooth  Crown 
Company." 

In  concluding  I  wish  merely  to  say  that  I  believe  in  giving  credit  where  credit 
is  due;  and  that  to  me  it  seems  chat  credit  is,  in  this  case,  undoubtedly  due  to  the 
man  who  devised  the  crown  and  bridge  that  has  stood  the  test  of  time,  and  promises 
to  stand  indefinitely,  rather  than  to  one  that  has  done  nothing  more  than  to  revive 
an  art  that  has  been  practiced  in  all  branches  of  metal  work  from  time  immemorial, 
that  probably  is  as  old  as  man's  knowledge  of  metals,  and  for  which,  at  this  late 
day,  great  claims  for  originality  are  made. 

As  to  the  kind  of  work  that  is  being  done  in  dentistry  along  that  line,  the  average 
result  is  described  by  Dr.  Rhein,  of  New  York,  who,  at  a  recent  dental  meeting, 
spoke  of  the  average  inlay  as  "A  floating  island  of  gold  in  a  sea  of  cement." 

Unless  the  average  practitioner  shall  learn  speedily  to  cast  better  inlays  and 
insert  them  with  greater  skill,  there  most  certainly  is  grave  danger  that  the  inlay 
method  will  bring  discredit   upon  the  entire  profession. 


EARLY  ATTEMPTS  AT  INLAY  CASTING 

By  C.   V.   Vignes,  D.D.S.,  New  Orleans,  La. 

Some  four  years  ago,  before  the  present  methods  of  gold  inlay  casting  came  in 
vogue,  and  before  I  had  heard  of  cast  gold  inlays,  I  made  some  attempts  at  casting 
gold  in  a  mold,  a  description  of  which  I  bslieve  will  be  of  interest. 

While  the  method  I  used  was  somewhat  different  from  that  now  employed,  and 
while  I  was  to  a  great  extent  unsuccessful,  yet  I  was  fortunate  enough  to  cast  a 
fairly  good  inlay.  And  having  been  so  close  to  the  right  way,  I  feel  pardonably 
proud  of  the  pioneer  work  that  I  did  in  that  direction,  although  it  was  abandoned  as 
impracticable,  even  unsuccessful. 

Working  upon  the  idea  that  the  duplicating  in  gold  of  wax  models  of  missing 
parts  of  teeth  would  greatly  facilitate  our  work,  I  made  the  following  experiments 
with  the  doubtful  success  above  mentioned: 

After  obtaining  an  impression  of  the  cavitj'  in  pink  paraffin  and  wax  and  carving 
to  contour,  as  is  at  present  done  with  the  special  inlay  wax,  I  attached  a  small  rope 


EARLY  ATTEMPTS  AT  IXLA  ]'  CAS'J-JNG  13 

of  the  sanif  material  tcj  tlie  model  to  form  a  sprue,  and  proceeded  to  imest  the  case. 
The  investment  was  made  small  and  without  the  ring  that  is  now  used  in  investing 
inlay  cases.  After  the  setting  of  the  investment,  a  funnel-shape  depression  was  made 
around  the  sprue. 

So  far  I  was  on  the  right  road  to  the  successful  casting  of  the  gold  inlay;  but  my 
idea  of  the  sprue  was  not  to  force  the  melted  gold  through  it,  nor  was  the  carved 
funnel  leading  to  the  sprue  to  be  used  as  a  crucible  in  which  to  melt  the  gold  prior 
to  its  being  forced  into  the  matrix  formed  by  the  disappearance  of  the  melted  model; 
but  the  funnel  and  sprue  were  made  to  facilitate  the  working  into  the  matrix  of  gold 
filings.  My  idea  being  that  if  I  could  fill  the  matrix  with  gold  filings  and  heat  the 
investment  (which  was,  for  that  purpose,  made  ver\'  small)  to  the  melting  point  of 
gold,  that  I  would  attain  the  result  sought  for;  but  in  this  I  was  mistaken,  for  I 
succeeded  only  in  obtaining  a  globule  of  gold. 

Following  up  the  first  idea,  I  thought  that  if  I  could  put  a  gold  lining  on  m\' 
model  that  I  would  meet  with  ultimate  success.  To  do  this  in  a  simple  manner  and 
to  obviate  the  necessity  of  burnishing  foil  into  the  cavity,  after  obtaining  my  model, 
I  rolled  it  into  gold  filings,  reinserted  it  into  the  cavity,  reburnished  it  and  proceeded 
as  before.  By  this  method  I  was  more  successful  than  in  my  first  attempt.  Failure 
was  due  to  the  fact  that  not  enough  of  the  gold  filings  investing  the  model  would 
adhere  to  the  investment  to  give  the  complete  metallic  lining  looked  for.  The 
casting,  while  it  had  the  general  shape  of  the  cavity,  w-as  too  defective  to  be  put  to 
practical  use.     Hence  the  abandoning  of  the  idea. 


TECHNIC  OF  A  CAST  GOLD  INLAY 

By  A.  F.  Miller,  D.D.S.,  Sandusky,  Ohio 

A  cavity  in  the  disto-occlusal  surface  of  an  inferior,  right  first  molar  was  prepared 
for  a  cast  gold  inlay  in  the  following  manner:  The  disto-buccal  and  disto-lingual 
margins  extended  to  beyond  the  point  of  contact.  All  sharp  angles  and  margins 
removed,  except  the  gingival  portion  at  which  point  the  surface  was  dressed  oflf  with  a 
fine  grit,  hard  rubber  safety,  separating  disk.  This  disk  being  flexible  can  be  extended 
under  the  free  margin  of  the  gum  with  little  discomfort  to  the  patient.  Excavation 
was  extended  to  the  occlusal  center,  cutting  out  the  sulcus  where  carious  and  so 
formed  that  the  wax  impression  can  be  freely  withdrawn.  The  above  method  of 
cavity  formation  presents  two  advantages:  first,  as  retaining  points  for  the  inlay; 
second,  the  removal  of  all  sharp  angles  and  margins  that  would  be  broken  down  in 
the  mold  by  the  action  of  the  cast  metal  against  them,  thus  preventing  proper  adapta- 
tion of  the  inlay  to  the  cavity.  This  cause  is  often  erroneously  attributed  to  shrink- 
age or  expansion  of  the  metal.  Gently  w^arm  the  wax  for  the  impression  over  a 
flame  and  press  it  into  the  cavity  with  the  finger  or  flat  burnisher,  instructing  the 
patient  to  close  the  mouth  for  occlusion.  Trim  off  all  excess  contouring  where  in- 
dicated, burnishing  the  wax  over  the  approximal  edges  and  carving  flush  to  the  oc- 
clusal margins.  Chill  the  wax  and  carefully  remove  from  the  cavity  with  a  small 
excavator.  Carve  a  horizontal  groove  in  the  wax  to  give  vertical  anchorage  to 
the  inlas'.  This  can  be  done  more  conveniently  after  the  sprue  wire  is  inserted. 
Heat  and  insert  sprue  wire  in  the  approximal  aspect  of  the  model  and  secure  it  in 
its  position  in  the  sprue  former  with  the  point  of  a  wooden  tooth  pick. 

The  first  investment  consisted  of  a  small  quantity  of  the  Detroit  investment 
compound  applied  with  a  soft  hair  brush,  covering  the  model  uniformly  to  about 


14  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

1-8  inch  thick,  extending  it  down  over  the  sprue  former.  This  is  then  invested  with 
a  second  mixture  of  equal  parts  of  3'ellow  molding  sand  and  plaster,  a  little  sodium 
chloride  added  to  hasten  setting,  and  flasked  in  a  split  rubber  tube  secured  from 
spreading  at  the  bottom  by  the  flange  at  the  sprue  former  and  by  an  open  metal  ring 
at  the  top. 

After  setting,  the  flask  is  removed  and  the  wax  and  moisture  eliminated  by 
laying  the  investment  horizontally  on  a  wire  screen  over  a  flame  on  a  case-heating 
stove  and  applying  the  brush  flame  from  the  blow-pipe  on  and  over  the  end  opposite 
the  gate.  This  procedure  required  only  fifteen  minutes  from  the  cime  the  invest- 
ment was  set,  including  the  casting;  the  inner  investment  showing  no  appreciable 
change  from  the  high  temperature  to  which  it  was  rapidly  subjected. 

It  is  claimed  by  the  demonstrator  that  the  outer  investment  serves  as  a  pro- 
tective envelope  to  the  inner  against  unequal  expansion  or  contraction,  thus  result- 
ing practically  in  an  inlay  uniform  and  without  shrinkage. 

The  instruments  used  in  preparing  the  cavity  were  Black's  rapid  excavator 
chisels,  a  German  short,  right  angle,  fissure  bur,  two  sizes,  and  fissure  stone  for 
right  angle. 

The  inlay  was  cast  on  a  vertical  centrifugal  casting  device  designed  by  the 
demonstrator. 

The  inlay  was  seated,  and  cemented  in  the  cavity  to  which  it  showed  perfect 
adaptation  at  every  point. 


PORCELAIN  CROWN  WITH  CAST  GOLD  BASE 

By  W.  A.  Sanderson,  D.D.S.,  Pittsburgh,  Pa. 

To  make  a  porcelain  crown  with  a  cast  gold  base,  proceed  as  follows: 

Select  a  tooth  of  any  make  desired,  either  fixed  or  detached  post. 

Prepare  root  in  usual  manner,  with  a  short  bevel  in  labial,  and  a  longer  bevel 
in  palatal  direction.  Grind  crown  roughly  to  place,  leaving  plenty  of  space  between 
the  crown  and  the  end  of  the  root  on  the  palatal  side.  Mold  a  small  piece  of  soft  inlay 
wax  about  the  pin  and  press  to  place  or  nearly  so.  Remove  and  trim  away  surplus 
wax.  Warm  slightly  and  press  home.  After  again  removing,  be  careful  to  remove 
all  wax  from  face  of  porcelain,  wipe  it  away  with  cotton  saturated  with  alcohol  or 
chloroform.  If  using  detachable  post  crown,  remove  the  porcelain,  attach  the  sprue 
wire  at  the  thickest  point  of  the  wax,  viz.,  at  the  palatal  heel.  Also  attach  another 
wire  (24  or  25  gauge)  at  a  point  as  near  the  labial  surface  as  is  possible.  When 
investing  pass  the  second  wire  through  a  hole  made  in  the  side  of  the  bucket  for  that 
purpose.  After  the  investment  has  set,  remove  the  sprue  and  both  wires.  The 
object  of  the  second  wire  is  to  provide  an  escape  for  the  air  or  gas  which  would  other- 
wise be  confined  in  the  mold. 

It  will  be  found  difficult  to  cast  the  gold  to  a  thin  edge  without  this  provision  for 
the  escape  of  gas. 

When  using  a  fixed  post  crown,  remember  that  it  is  impossible  to  overheat  with 
natural  gas  and  blow-pipe,  and  the  hotter  the  case  the  less  liable  is  the  porcelain  to 
check. 

After  casting,  smooth  with  paper  discs  and  polish.  The  result  will  be  a  perfect 
adaptation  to  root  and  crown.  In  cases  of  enlarged  root  canal  the  wax  and  con- 
sequently the  gold  can  be  forced  up  on  the  post,  thus  gi\ing  extra  strength  and  a 
perfect  adaptation  of  the  post  to  the  root. 


SHRINKAGE  OF  THE  INVESTMENT— INVESTING    THE    WAX    MODEL 

SO  AS  TO  PROCURE  THE  MINIMUM  POSSIBILITY 

OF  DISTORTION 

By  C.  J.   Clark,   D.D.S.,   Chicago,   111. 

The  instability  cf  the  investment  used  for  the  purpose  of  terming  the  mold 
into  which  the  molten  metal  is  forced,  has  been  considered  the  prime  factor  in 
contributing  to  the  cause  of  many  failures  in  the  process  of  casting  gold  under 
pressure.     It  being  charged — 

1st.  That  the  investment  being  porous,  allows  the  pressure  to  envelop  the 
m(?ltcn  metal  in  the  mold,  causing  distortion  and  augmenting  the  shrinkage  cf  the 
metal. 

2nd.  That  the  investment  is  not  of  sufficient  integrity  to  withstand  the  contact 
of  the  molten  metal  when  considerable  pressure  is  used  to  force  the  molten  metal 
into  the  mold. 

3rd.     That  the  investment  shrinks,  thereby  causing  a  distortion  cf  the  mold. 

THE    POROSITY    OF    THE   INVESTMENT 

The  porosity  of  the  investment  can  be  considered  as  a  detrimental  factor  only 

in  cases  where  the  force  used  to  drive  the  metal  into  the  mold  is  an  expanding  gas 

and  in  an  extensive  piece  of  work,  the  pressure  not  being  restricted  to  exert  its  force 

on  the  metal  in  the  crucible,  but  being  free  to  penetrate  the  investment  by  virtue  cf 

%-/  -TigJ  ^»  ^ 


its  porosity,  and  to  envelop  and  attack  the  metal  on  all  surfaces,  thereby  causing 
compression  from  several  directions,  and  must  exert  a  deleterious  influence  on  the 
finished  product. 

Before  a  cast  is  made  the  mold  contains  air,  and  when  the  metal  is  forced  into 
the  meld,  it  must  displace  the  confined  air  and  expel  it  into  the  porous  in\estment, 
where  it  meets  and  offers  opposition  to  and  impedes  the  free  expulsion  cf  air  from  the 
meld,  thereby  retarding  the  ingress  of  the  metal  into  the  mold. 

THE  INTEGRITY  OF  THE  INVESTMENT 
When  we  consider  the  extreme  fluidit}-  of  the  molten  metal,  if  judgment  is 
exercised,  there  is  no  danger  from  this  source;  for  the  molten  metal  is  in  such  a  state 
as  to  be  incapable  of  making  any  impression  on  the  walls,  angles  and  convolutions 
of  the  mold  as  it  might  if  in  a  more  coherent  condition.  The  direct  opposite  is  true, 
the  walls,  angles  and  convolutions  of  the  mold,  imprint  their  e\ery  reflection  on  the 
surface  of  the  molten  metal,  and  unless  an  excessive  force  be  used,  there  is  no  danger 
of  distorting  the  mold  from  the  impact  of  the  molten  metal. 


16 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


THE    SHRINKAGE    OF    THE    INVESTMENT 

Let  US  suppose  Fig.  1  to  represent  a  bar  of  iron  36  in.  in  length  and  12  in.  in 
width,  and  of  equal  density  throughout  the  mass.  Under  a  definite  degree  of  heat 
it  will  expand  to  the  extent  of  3-24  of  an  inch  in  each  direction  from  its  mean  line 


^^3 


of  linear  expansion  and  1-24  inch  in  each  direction  from  its  mean  line  of  lateral 
expansion.  The  dimensions  of  the  bar  would  then  be  36  +  3-24  +  3-24  =  36  6-24 
+  12  +  1-24  +  1-24  =  12  2-24  or  36  6-24  +  122-24  as  represented  by  Fig.  1. 
Now  let  us  suppose  that  the  same  bar  is  bent  into  the  form  of  a  ring,  the  inner  cir- 
cumference of  which  would  measure  36  in.  with  a  consequent  diameter  of  approxi- 
mately 12  in.  (The  diameter  of  a  circle  being  determined  by  dividing  the  circum- 
ference by  three  and  a  fraction,  the  fraction  being  omitted  to  simplify.)  The 
dimension  of  the  outer  circumference  is  immaterial.  Now  if  the  same  definite  degree 
of  heat  be  applied  as  was  to  the  straight  bar,  we  will  discover  that  while  the  dimen- 
sion of  the  outer  circumference  has  increased,  the  dimension  of  the  inner  circum- 


^^•5 


ference  remains  unchanged.  F"or  the  simultaneous  increase  of  the  outer  and  inner 
dimension  of  the  respective  circumferences,  without  taking  into  consideration  the 
lateral  expansion  of  the  ring,  would  form  a  ring  the  inner  circumference  of  which 
would  measure  36  6-24  with  a  resultant  diameter  of  12  2-24  (Fig.  3).  But  the 
lateral  dimensions  of  the  ring  are  increased  by  expansion  to  the  extent  of  1-24  inch 
in  each  direction  from  the  mean  line  of  lateral  expansion  (see  Fig.  3  and  note  dotted 
lines)    thereby  increasing  the  lateral  dimension  of  the  ring  toward  the  center  of  the 


SHRINKAGE  OF  THE  INVESTMENT 


17 


inner  circumference,  thus  decreasing  the  dimension  of  the  diameter  1-24  inch  at  any 
and  every  point  on  the  inner  circumference  of  the  ring,  or  12  2-24 — 2-24  =  12  in., 
the  2-24  decrease  in  the  dimension  of  the  diameter  due  to  lateral  expansion,  offsetting 
the  2-24  inch  gained  by  the  6-24  inch  increase  of  the  circumference.  Therefore,  the 
diameter  of  the  inner  circumference  will  measure  12  in.,  being  identical  to  the  measure- 
ment of  the  diameter  before  e.xpansion  occurred.  Thus,  when  the  lateral  measure- 
ment (B.  C,  Fig.  1)  of  an  iron  ring  equals  the  diameter  of  the  inner  circumference  of 
the  ring  (Fig.  1  D.  E.)  should  any  expansion  or  contraction  occur,  the  dimension 
of  the  diameter  of  the  inner  circumference  remains  unaltered.  Let  F"ig.  4  represent 
a  ring,  the  circumferential  dimensions  of  which  arc  identical  to  Fig.  2,  but  with  the 
inner  circumference  eccentric  to  the  outer  circumference  to  the  extent  as  shown  in 
diagram  4.  The  lateral  dimensions  of  the  ring  being  no  longer  uniform,  should  an>' 
expansion  occur,  it  would  vary  in  proportion  to  the  changing  lateral  dimension. 
Thus,  where  the  lateral  dimension  measures  24  in.,  the  expansion  would  be  2-24  in. 
in  each  direction  from  the  mean  line  of  e.xpansion;  or  an  expansion  of  2-24  in.  toward 
the  center  of  the  inner  circumference,  which  would  cause  a  decrease  in  its  diameter 


j^y^-6 


^i^-7. 


of  2-24  in.  at  that  point,  and  where  the  lateral  dimensions  measure  12  in.  the  ex- 
pansion would  cause  an  increase  of  1-24  in.  in  each  direction  from  the  mean  line  of 
lateral  expansion,  with  a  corresponding  decrease  of  the  diameter  of  the  inner  circum- 
ference, at  that  point.  Therefore,  the  lateral  expansion  would  be  of  an  unequal 
and  varying  degree  throughout  the  ring,  registering  the  same  varying  degrees  of 
inequality  upon  the  inner  circumference  of  the  ring.  Hence,  the  inner  circum- 
ference would  no  longer  maintain  the  lines  of  a  perfect  circle,  and  the  ring  would  be 
described  as  having  become  warped  and  the  inner  circumference  distorted. 

Now  these  same  laws  which  govern  the  expansion  of  an  iron  ring,  are  also 
applicable  to  contractions,  and  also  to  any  substance  capable  of  exercising  the 
property  of  expansion  or  contraction.  For  instance,  investment  material  would  be 
included,  it  having  a  tendency  to  shrink  under  the  application  of  terrific  heat.  Suppose 
we  desire  to  cast  a  perfect  ball;  if  the  wax  model  was  surrounded  by  an  investment 
of  equal  consistency,  held  by  a  flask  in  the  form  of  a  globe  (Fig.  2  could  be  applied  as 
cross  section),  and  the  thickness  of  the  investment  equaled  the  diameter  of  the  wax 
model,  should  expansion  or  shrinkage  occur,  the  dimensions  of  the  mold  would  remain 
unchanged.  Again,  suppose  we  desire  to  cast  a  perfect  ball,  but  the  model  is  placed 
eccentric  to  the  external  surface  of  the  investment  (to  which  Fig.  4  could  be  applied 
as  a  cross  section)  so  that  the  in\('stmont  would  be  of  une(]ual  anfl  \arying  thickness, 


18  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

then  should  any  expansion  or  contraction  occur,  it  would  be  unequal  in  proportion; 
as  the  lateral  dimensions  are  unequal  and  the  effect  would  be  registered  on  the  walls, 
angles  and  convolutions  of  the  mold,  and  the  investment  would  be  described  as 
warping,  and  the  mold  as  being  distorted.  Now  again,  let  us  suppose  it  is  desired  to 
cast  a  perfect  ball,  but  in  an  ordinary  flask  used  for  dental  purposes.  Now,  if  the 
wax  model  is  attached  to  the  sprue  wire  and  mounted  on  the  crucible  former,  and  the 
model  encapsuled  by  investment  of  uniform  thickness,  equal  to  diameter  of  the 
model,  (see  Fig.  5)  and  after  this  has  cr^'stallized,  place  the  flask  over  it,  and  com- 
pletely fill  it  with  investment  material  (Fig.  6).  Then  should  any  shrinkage  occur 
during  the  process  of  obliterating  the  model,  or  fusing  the  gold  in  the  crucible,  it 
would  be  incapable  of  exerting  any  deleterious  effect  on  the  mold.  And  for  this 
reason — that  the  continuity  between  the  first  and  second  stratum  of  investment  is 
broken  and  should  any  shrinkage  in  the  second  stratum  of  investment  occur — it 
being  of  unequal  thickness — the  effect  of  the  shrinkage  on  the  mass  would  be  unequal; 
but  the  continuity  between  the  first  and  second  stratum  being  broken,  the  second 
stratum  would  draw  away  from  the  first  stratum  causing  no  distortion  to  ic  (the 
first  or  inside  stratum)  and  should  the  mass  comprising  the  first  stratum  subse- 
quently shrink,  this  mass  being  of  uniform  thickness  and  equal  in  measurement  to 
the  diameter  of  the  model,  should  any  shrinkage  occur  the  form  of  the  mold  would 
practically  be  unaltered  (Fig.  7).  Hence,  during  the  process  of  investing  a  model 
for  the  purpose  of  making  a  matrix  or  mold  for  the  casting  of  gold  or  any  metal  under 
pressure,  if  the  model  is  encapsuled  by  a  stratum  of  investment  of  uniform  thickness 
and  equal  to  the  thickness  of  the  model,  and  be  allowed  to  crystallize,  and  then  this 
surrounded  by  the  flask  and  enveloped  by  a  second  stratum  of  investment,  it  is,  for 
all  practical  purposes,  a  geometrical  impossibility  to  distort  the  mold,  should  shrink- 
age of  the  investment  occur.  The  operator  can  exercise  his  ingenuity  to  an  unlimited 
degree,  in  investing  to  the  best  advantage,  rnodels  taken  from  compound  approximal 
cavities  including  occlusal  fissure  cavities  and  copings,  so  that  only  an  infinitesimal 
degree  of  distortion  can  possibly  occur,  should  the  investment  shrink  or  even  check. 


METHOD  OF  RESTORING  BICUSPID  ROOTS  TO  USEFULNESS 

By  Auber  Peebles,  D.D.S.,  Wilmington,  Ohio 

There  are  roots  of  superior  bicuspids  sacrificed  many  times,  when  a  little  time 
and  careful  effort  would  make  good  foundations  for  the  support  of  strong  and 
serviceable  crowns. 

In  this  case  decay  has  extended  to  such  a  distance  that  separation  at  the  bifurca- 
tion has  taken  place.  These  roots,  which  are  so  often  extracted,  are  disinfected,  filled 
and  so  shaped,  that  small  gold  caps  may  be  made  to  fit  each  one  accurately;  and  in 
each  cap  an  iridio-platinum  pin  is  soldered  as  for  a  Richmond  crown.  These  caps 
with  pins  attached  are  removed  in  impression  and  mounted  on  model  of  investing 
material  so  as  to  be  able  to  solder  over  ends,  an  oval  piece  of  platinum  plate  about 
28  or  30  gauge:  then  you  have  the  foundation  for  a  crown. 

The  remainder  of  crown  is  made  by  adjusting  a  facing  of  suitable  size  and  color 
to  correspond  with  the  other  teeth,  and  after  backing  it  with  40  gauge  24k.  gold, 
wax  up  an  inner  cusp  to  properly  occlude  with  lower  teeth,  and  invest  in  casting  ring. 
After  casting  with  18  or  20k.  gold  direct  to  backing,  polish  and  you  have  a  very 
strong  and  very  serviceable  crown  instead  of  a  bridge,  which  would  have  been  neces- 
sary had  roots  been  extracted. 


A  THEORETIC  CONSIDERATION  OF  THE  EXPANSION  AND  CON- 
TRACTION OF  GOLD  WHEN  CAST  UNDER  PRESSURE 
By  C.  J.  Clark,  D.D.S.,  Chicago,  HI. 

One  of  the  perplexing  questions  that  has  confronted  the  dental  profession,  and 
been  the  subject  of  controversy  and  discussion  since  the  process  of  casting  metal 
under  pressure  has  been  practiced,  is  the  question  of  shrinkage  and  expansion. 
Of  all  the  literature  I  have  read  pertaining  to  this  intricate  subject  I  have,  so  far, 
failed  to  find  anything  that  gave  a  correct  exposition  of  this  question,  or  depicted  a 
true  scientific  portrayal  of  the  metamorphosic  phenomena  the  metal  undergoes  in 
its  transition  from  the  molten  to  the  solid  state. 

I  have  read  ably  written  papers  comparing  the  shrinkage  of  gold  when  cast 
under  pressure,  to  the  shrinkage  of  steel  rails.  I  have  perused  columns  of  figures, 
carefully  compiled,  showing  the  degree  of  expansion  and  contraction  of  gold  under 
normal  conditions,  but  this  is  immaterial  and  not  applicable;  on  the  contrary,  it  is 
flagrantly  fallacious  when  applied  to  gold  cast  under  pressure,  while  the  molten 
metal  is  confined  within  the  unyielding  embrace  of  rigid  walls. 

Of  all  the  mechanical  achievements  that  man  can  boast,  there  is  not  one  that  is 
not  a  modification  of  some  mechanical  principle  utilized  in  the  unfathomed  labora- 
tories of  nature.  In  regard  to  the  art  of  molding  and  casting,  the  same  cosmic 
laws  prevail  with  infallible  accuracy,  whether  the  proportions  are  the  seething  molten 
mass  of  an  uncooled  planet,  or  an  insignificant  globule  of  gold  no  larger  than  a  pea. 
Science  teaches  that  the  planets  and  all  the  solar  system  once  existed  in  the  form 
of  nebulous  or  gaseous  matter,  scattered  throughout  the  boundless  oceans  of  space, 
whirling  and  revolving,  gradually'  cooling  and  growing  denser,  throwing  olT  portions 
from  what  we  may  term  parent  bodies,  and  these  cast  off  portions  in  turn  throwing 
off  other  portions  from  their  mass,  until  this  sort  of  process  in  time  evolved  our 
solar  system. 

So  for  countless  ages  the  matter  of  this  earth  existed  in  a  molten  state,  gradually 
cooling  and  shrinking  until  the  surface  became  rigid  and  the  internal  molten  mass 
became  encapsuled  by  a  crust.  As  the  shrinkage  continued,  matter  was  called  upon 
to  supply  the  deficiency,  and  the  crust  being  solid  and  rigid  and  held  by  the  power  of 
cohesion,  the  power  of  centrifugal  force  was  greatest  at  the  greatest  circumference, 
and  of  course  the  portion  of  the  revolving  sphere  that  offered  the  least  resistance 
(the  poles)  succumbed  to  the  demands  of  the  internal  shrinkage  and  were  drawn 
inward;  and  so  we  find  the  earth  slightly  concave  at  the  poles. 

The  cooling  of  the  metal  in  a  mold,  while  not  exactly  similar,  is  strikingh- 
analogous  to  the  cooling  of  a  planet  or  the  earth  on  which  we  live. 

Matter  is  never  at  rest;  the  atoms  comprising  the  molecules  revolving  around  a 
common  center,  forming  a  miniature  solar  system,  are  in  a  constant  state  of  agitation, 
moving  rapidly  around  in  their  medium  of  ether,  and  confined  in  their  movement 
to  the  limited  space  between  their  fellows. 

Now  the  outer  surface  of  a  mass  of  matter  is  the  first  to  be  susceptible  to  any 
thermal  change,  the  effect  being  transmitted  toward  I  he  center,  and  if  this  thermal 


20  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

change  be  of  a  sufficiently  high  degree  to  change  the  state  of  the  mass  from  the  soHd 
to  the  liquid,  or  gaseous,  or  vice  versa,  the  surface  is  the  first  to  exhibit  these  mani- 
festations.     (Fig.  1.) 

Fig.l 


Let  us  suppose  Fig.  1  to  represent  a  cross  section  of  gold  plate,  magnified  to 
such  an  extent  that  the  molecules  are  visible,  and  represented  by  the  small  circles 
or  spheres.  Now,  should  this  plate  be  subjected  to  a  heat  of  a  sufficient  degree,  the 
atoms  of  the  molecules  revolve  more  rapidly  than  before,  become  more  divergent 
in  their  tendency,  describing  a  larger  circumference  about  their  common  center,  the 
molecules  increase  in  the  same  proportionate  volume,  and  their  mutual  power  of 
cohesion  diminishes,  and  this  allows  the  molecules  to  separate  more  widely,  and 
permits  of  a  greater  latitude  in  which  to  exercise  their  mobility.  As  the  atoms  are 
whirling  about  their  common  center  the  molecules  are  revolving,  and  revolving  also 
about  each  other,  generating  centrifugal  force  to  such  an  extent  as  to  overcome  the 
force  of  gravity,  and  with  a  tendency  towards  projection  in  every  direction;  held  in 
restraint  only  by  the  still  active  but  greatly  diminished  power  of  cohesion.  This 
causes  some  molecules  to  be  lifted  above  their  fellows  and  as  heat  increases  the  mass 
begins  to  assume  a  globular  form  (Fig.  2),  and  presents  a  panorama  of  rhythmic 
harmonious  action. 


Now  if  the  heat  be  withdrawn  the  revolutions  of  the  atoms  about  their  common 
centers  decrease,  and  as  their  momentum  gradually  diminishes  the  atoms  come  into 
closer  proximity,  the  molecules  decrease  in  volume,  the  power  of  cohesion  increases, 
the  mutual  attraction  of  the  molecules  becomes  more  intense,  exhibiting  more  in- 
fluence than  the  force  of  gravitation,  and  the  congealing  mass  of  metal  retains  more 
or  less  of  the  globular  form;  the  molecules  being  caught  in  the  act  of  falling  much 
the  same  as  water  is  caught  and  held  in  the  formation  of  an  icicle,  see  Fig.  3. 

The  duration  of  time  in  which  the  metal  is  transformed  from  a  molten  to  a  solid 
state  is  exceedingly  short,  and  the  fact  that  the  metal  retains  enough  heat  to  main- 
tain a  red  color  for  a  time,  furnishes  no  scientific  proof  that  the  metal  in  the  mold 
will  shrink,  for  the  metal  that  remains  in  the  crucible  and  the  metal  in  the  mold 
encounter  conditions  in  hardening  that  are  diametrically  opposed.  The  metal  in 
the  crucible  is  confined  by  no  walls,  and  the  pressure  on  it  being  from  without  inward 
has  no  suchefifect  as  on  that  confined  in  a  mold,  for  the  reason  that  the  hydraulic 
I)ressure  that  the  confined  gold  is  subjected  to  forces  the  metal  from  the  center  out- 
wardly as  long  as  it  remains  molten,  and  thus  it  is  pressed  against  the  cooler  walls 
where  the  crust  as  described  is  formed,  and  which  will  register  a  density  of  19.45, 


EXPANSION  AND  CONTRACTION  OF  GOLD  21 

against  19.16  of  that  remaining  in  the  crucible,  and  there  is  no  inherent  force  or 
physical  property  in  the  metal  itself  after  being  cast  under  pressure  capable  of  aug- 
menting its  density  to  any  further  degree,  so  it  is  physically  impossible  for  it  to 


Fis-,  3 


shrink.  Therefore,  if  in  the  process  of  making  an  inlay  or  a  more  extended  piece  by 
casting  under  pressure  any  distortion  occurs,  or  it  is  not  a  fac-simile  of  the  wax 
model,  the  discrepancy  must  be  ascribed  to  some  other  factor  or  cause  than  the 
shrinking  of  the  gold. 

References  consulted  on  Expansion  and  Contraction  of  Metals: 

(Chicago  Public  Library.) 
Clark,  D.  K.    A  Manual  of  Rules,  Tables  and  Data  for  Mechanical  Engineers.    1878.  *K  598. 
DuBois,  A.  J.    Elementary  Principles  of  Mechanics.    Vol.2.    1894.    K  4982,2. 
Dana,  E.  S.  (ed.)  American  Journal  of  Science.    Vol.  161.    1901.    Ser. 
Howe,  H.  M.    Metallurgical  Laboratory  Notes.    1902.    K  12780. 
Hutton,  W.  S.    Practical  Engineer's  Hand-Book.    1896.    K  5405. 
Lineham.  VV.  J.    Text-Book  of  Mechanical  Engineering.    1894.    K  4958. 
Poynting,  J.  H.  and  Thomson,  J.  J.    Text-Book  of  Physics.    1904.    K  15930,.3. 
Rankine,  W.  J.  M.    Manual  of  Civil  Engineering.    1891.    K661. 
Useful  Rules  and  Tables.    1873.    K  665. 

Thurston,  R.  H.    Brasses,  Bronzes  and  Other  Alloys.    1900.    K  5502,3. 
Watson,  W.    Text-Book  of  Physics.    1905.    K  15933. 

If  this  globule  of  gold  were  measured  for  its  specific  gravity'  it  would  be  found 
that  it  developed,  by  the  mutual  attraction  of  its  molecules  (cohesion)  a  density  that 
registers  a  relative  specific  gravity  of  19.16.  Thus,  if  gold,  heated  so  as  to  assume 
the  liquid  state,  be  allowed  to  congeal  uninfluenced  by  any  interfering  conditions, 
the  only  factors  entering  into  the  phenomena  being  mass,  cohesion,  heat,  molecular 
mobility,  volume  and  gravitation,  it  is  a  physical  impossibility  for  the  metal  to 
develop,  by  virtue  of  its  cohesive  force,  a  density  that  registers  a  relative  specific 
gravity  above  19.16.  In  the  casting  of  metal  under  pressure,  additional  factors 
enter,  and  must  be  taken  into  consideration;  they  are  hydraulic  pressure  and  welding, 
the  latter  being  induced  by  the  force  of  hydraulic  pressure. 

If  a  mold  has  been  prepared  in  the  usual  procedure  for  a  cast  under  pressure, 
and  is  in  a  condition  for  the  reception  of  the  molten  metal,  a  button  of  gold  fused  in 
the  crucible  manifests  the  same  physical  phenomena  previously  described  and 
represented  by  Fig.  2.  The  atoms  will  revolve  around  their  common  center  more 
rapidly  than  at  a  lower  temperature,  and  the  molecules  will  revolve  around  each 
other  in  like  manner  and  the  metal  is  gradually  transformed  from  the  solid  to  the 
molten  or  liquid  state.  If  force  now  be  suddenly  applied  to  the  liquid  mass  in  the 
crucible  a  portion  of  it  will  be  forced  by  displacement  into  the  mold,  and  if  the 
pressure  be  maintained  for  a  time  it  will  be  transmitted  from  molecule  to  molecule 
simultaneously  in  every  conceivable  direction,  the  hydraulic  force  pressing  the  mole- 
cules to  all  surfaces  and  angles  of  the  mold.  As  the  molecules  at  the  surface  of  the 
mass  come  in  sudden  contact  with  the  walls  of  the  mold,  their  movements  are 
abruptly  checked,  the  atoms  of  the  molecules  are  forced  to  closer  proximity,  the 
molecules    decrease    in  volume  and   have  less  latitude  in  which   to  exercise  their 


22 


PRACTICAL   MANUAL   OF    DENTAL    CASTING 


mobility,  which  instantly  induces  congealation;  and  as  they  are  held  firmly  against 
the  walls  of  the  mold,  gaps  and  crevices  occur,  which  are,  however,  filled  by  the 
pressure  behind,  and  with  inconceivable  rapidity,  with  new  recruits,  frenzied  and 


fi&4 


heat-maddened,  where  they  meet  the  same  fate  as  their  fellows,  crushed  and  jammed 
against  each  other  and  the  walls  of  the  mold  until  in  congealing  a  rigid  wall  or 
capsule  lines  every  surface  and  angle  of  the  mold.     (See  Fig.  4.) 

This  goes  on  in  the  same  way  until  the  surface  crust  thickens  to  the  center,  all 
following  the  same  regular  order  of  things,  but  with  no  loss  of  appreciable  time,  in  a 
small  mass  of  gold  as  might  be  inferred  from  the  deliberate  description.  This  metal 
will  be  found  to  be  of  higher  specific  gravity  than  when  it  is  allowed  to  cool  under 
ordinary  conditions.  A  pressure  of  12  pounds  induced  by  expanding  gas  will  bring 
about  a  density  or  specific  gravity  of  19.45. 


TELESCOPIC  CROWN  FOR  BRIDGE  WORK 

By  E.  L.   Kanaga,  D.D.S.,   Philadelphia,  Pa. 

No.   1.     A  piece  of  metal  for  the  band  is  cut  from  30-gauge  coin  gold,  the  oc- 
clusal end  being  1-32  of  an  inch  smaller  than  the  gingival. 
No.  2.     Showing  the  band  joined  sweated. 
No.  3.     The  floor  sweated  to  the  band. 


No.  4.  The  core  is  formed  by  holding  the  inner  cap  in  a  paper  form  and 
pouring  fusible  metal  into  it. 

No.  5.  The  outer  cap  is  made  l)y  dri\'ing  the  inner  cap,  now  mounted  on  the 
core,  into  it. 

No.  6.     Shows  method  of  obtaining  contour. 


THE  EXTENT  TO  WHICH  THE  CASTING  PROCESS  MAY  BE 

ADVANTAGEOUSLY  APPLIED  TO  CROWN  AND 

BRIDGEWORK 

By  Hart  J.  Goslee,  B.S.,  D.D.S..  Chicago 

The  full  extent  to  which  the  application  of  the  casting  process  may  have 
revolutionized  the  practice  of  dentistry  is,  of  course,  difificult  to  determine,  but 
it  is  safe,  I  think,  to  say  that  its  influence  has  been,  and  is  now  being,  felt  to  a 
greater  or  less  extent  by  even  the  most  obscure  dentists  in  the  most  remote  districts. 

Whether  all  who  are  now  doing  casting  in  some  form  or  other  will  care  to 
acknowledge  it,  or  whether  they  will  concede  its  revolutionary  influence,  and  the 
marked  advancement  made  possible  by  its  application,  or  not,  may  be  a  question; 
but  that  at  least  a  very  large  percentage  of  dentists  are  doing  casting,  and  that 
they  are  doing  better  work,  and  doing  it  with  infinitely  greater  comfort  to  their 
patients  and  with  the  expenditure  of  less  nervous  energy  on  their  own  part  than 
they  formerly  did,  there  can  be  no  question. 

That  some  are  much  more  enthusiastic  over  its  possibilities  than  others,  and 
that  some  are  getting  much  better  results  than  others  is  also  unquestionable, 
and  it  is  as  interesting  as  it  is  true. 

However,  this  is  but  a  natural  sequence  and  should  be  expected  in  any  field 
of  effort  in  which  former  accepted  practices  and  methods  of  long  standing  become 
so  completely  revolutionized  and  supplanted,  if  you  please,  in  so  short  a  period  of 
time;  where  the  pedestals  upon  which  the  cherished  reputations  of  so  many 
prominent  practitioners  were  made  to  crumble  and  totter,  almost  in  a  day;  where 
old  and  young  must  begin  anew  and  alike,  and  where  the  application  of  this 
newer  practice  and  its  practicability  must  necessarily  be  tinctured  with  a  saturated 
solution  of  personal  equation. 

From  the  beginning,  however,  it  has  been  interesting  to  note  that  those  who 
were  early  to  grasp  the  possibilities  of  casting  and,  hence,  who  have  been  and  are 
still  doing  the  most  of  it,  are  the  most  enthusiastic  over  it,  and,  therefore,  does  it 
not  naturally  follow,  by  the  same  rule  of  thumbs,  that  those  who  were  first  to 
grasp  and  accept  its  wonderful  possibilities,  who  have  been  and  are  still  doing 
the  most  of  it,  and  who  are  most  enthusiastic  over  it,  are  also  the  ones  who  are 
obtaining  the  best  results? 

While  it  may  be  true  that  the  proportion  of  those  who  ever  attain  to  the  verj' 
highest  achievements  in  any  mechanical  pursuit  is  not  a  large  one,  still  I  am  of  the 
very  firm  belief  that  the  casting  process  has  afforded  an  opportunity  for  raising 
the  standard,  and  increasing  the  percentage  of  uniformly  good  results;  and,  in 
the  light  of  our  present  achievements,  that  this  standard  will  become  higher  and 
higher  in  proportion  as  we  recognize  our  own  personal  limitations,  and  realize  the 
full  scope  of  its  possibilities. 

Those,  who  by  a  process  of  self-analysis,  maj'  thus  recognize  their  own  limi- 
tations will  not  expect  a  mechanical  process,  or  a  machine  of  any  make  or  kind, 
to  adjust  and  adapt  itself  to  the  varying  and  intricate  demands  of  an  e.xacting 


24,  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

line  of  work,  unless  the  process  is  followed,  or  the  machine  operated,  with  an 
average  degree  of  human  intelligence,  but  those  who  fail  to  recognize  this  are 
surely  destined  to  meet  with  failure. 

Thus  it  is  more  than  probable  that  many  may  have  failed  in  attaining  to 
the  heights  of  even  average  success  simply  because  they  expected  too  much  of  the 
process  involved,  and  exacted  too  little  of  themselves,  but  those  in  this  class  never 
become  enthusiasts,  and  those  who  never  become  enthusiasts  rarely  become 
experts  in  any  line. 

Enthusiasm,  expertness  and  all  that  goes  with,  to  make  for,  and  insure, 
success  in  the  application  of  any  mechanical  process  can,  after  all,  come  only 
from  the  "man  behind  the  gun,"  and  hence  the  operator  who  aspires  to  such 
must  be  willing  to  acknowledge  this  fact  and  contribute  his  share;  and  in  this 
instance  his  share  is  in  the  form  of  ammunition,  and  the  ammunition  now  needed 
most  of  all  is  correct  and  accurate  technique. 

While  the  factor  of  personal  equation  will  necessarily  demand  a  more  or  less 
different  technique  for  each  and  every  operator,  yet  the  most  scrupulous  attention 
to  details,  and  the  utmost  of  accuracy  is  necessary  in  each  instance,  and  as  such  a 
technique  is  to  be  acquired  only  at  the  expense  of  time,  thought  and  energy,  it  is 
scarcely  purchasable,  nor  may  it  result  from  delegating  important  parts  of  the 
work  to  laboratories,  or  to  inexperienced  or  unskilled  assistants,  as  is  a  common 
but  bad  practice. 

When  the  average  operator  realizes  these  essentials  to  success,  then  the 
average  operator  may  reasonably  hope  to  rise  above  the  average  and  achieve 
success  in  the  application  of  the  casting  process,  and  as  he  appreciates  them  will 
he  also  find  the  field  of  usefulness  broaden  and  the  possibilities  become  more  and 
more  unlimited. 

If  there  were  no  field  to  which  the  casting  process  may  be  applied  other  than 
the  one  which  embraces  the  filling  of  teeth,  however,  let  me  ask  you  what  a  long- 
felt  want  would  it  still  afford;  what  a  broad  field  of  usefulness  would  it  occupy; 
what  a  priceless  advancement  would  it  mark  in  the  preservation  and  restoration 
of  the  teeth,  since  it  is  now  generally  conceded  that  the  inlay  affords  a  better, 
quicker,  less  painful  and  probably,  on  the  average,  more  permanent  character  of 
operation? 

Granting  all  of  this  to  be  true,  however,  the  limitations  of  this  process  have 
by  no  means  yet  been  reached.  Indeed,  it  seems  that  they  are  still  only  in  their 
infancy,  and  that  the  field  of  usefulness  as  applied  to  all  other  phases  of  practical 
dentistry  is  as  broad  and  far-reaching  as  is  the  degree  and  character  of  success 
already  insured  in  the  filling  of  teeth. 

While  this  is  undoubtedly  true,  to  a  greater  or  less  extent,  as  applied  to  the 
whole  field  of  dental  prosthesis,  it  is  particularly  true  as  applied  especially  to  the 
subject  which  it  is  my  purpose  to  discuss  at  this  time — that  of  crown  and  bridge 
work. 

But  a  few — a  very  few — years  ago  this  line  of  our  work,  which  many  of  us 
are  now  pleased  to  designate  and  dignify  as  a  "specialty,"  was  but  an  indetermin- 
able collection  or  mass  of  empirical  details.  Almost  every  dentist  had  his  own 
ideas,  and  his  own  methods,  and  each  differed  from  the  other  to  such  an  extent 
as  to  confuse  the  teacher,  and  bewilder  the  beginner,  in  every  respect  and  direction 
except  one — the  display  of  gold. 

For  many  years  patients  wearing  crown  or  bridge  work,  however  limited  or 


CASTING  PROCESS  APPLIED  TO  CROWN  AND  BRIDGEWORK         25 

extensive  in  character,  were  involuntary  advertising  mediums  for  dental  jewelers; 
were  forced  to  display  shocking  evidences  of  a  handicraft  which,  while  in  some 
instances  useful,  perhaps,  were  usually  far  short  of  art,  and  always  more  or  less 
repulsive. 

These  evidences,  I  am  sorry  to  say,  may  still  be  obser\'ed,  but  fortunately 
not  to  the  same  extent.  As  a  profession,  we  are  beginning  to  strive  for  higher 
ideals  in  the  art  side  of  our  work,  and  in  this  respect  we  are  aided  materially  by 
the  demands  of  an  ever-increasing  degree  of  culture  on  the  part  of  our  patients. 

Since  porcelain  has  always  been  and  is  still  the  one  substance  which  most 
closely  simulates  nature,  and  therefore  best  meets  the  requirements,  this  fact, 
together  with  these  combined  ambitions  on  the  one  part,  and  demands  on  the 
other,  must  lead  one  to  conclude  that  more  porcelain  and  less  gold  must  be  used 
in  an  effort  to  satisfy  each. 

While  this  was  recognized  many  years  ago,  still  the  inherent  element  of  struc- 
tural weakness  so  characteristic  of  porcelain,  and  so  often  learned  from  sad 
experiences,  together  with  the  knowledge  that  cosmetics  was  but  one  requirement, 
and  that  in  the  construction  of  all  forms  of  crowns  and  bridges  the  actual  mechan- 
ical requirements  of  strength  and  accuracy  of  adaptation  must  necessarily  receive 
first  consideration,  it  is  no  great  wonder  that  cosmetics  was  accordingly  sacrificed. 

If  it  were  not,  and  if  it  is  not,  possible  to  obtain  both  of  these  requirements 
at  one  and  the  same  time,  then  cosmetics  should  be  placed  second  to,  or  sacrificed 
for  the  purely  mechanical,  but  the  possibilities  of  casting  offer  opportunity  for 
obtaining  all  of  the  combined  requirements  to  the  very  highest  degree,  and  hence 
its  application  may  be  made  to  practically^  revolutionize  all  of  our  former  methods. 

This  is  possible  because  the  casting  process,  skilfully  utilized,  insures,  first, 
accuracy  of  adaptation,  and,  second,  a  maximum  of  strength  with  a  minimum  of 
gold:  and  in  the  proportion  as  the  amount  of  gold  necessary  to  insure  strength 
may  be  decreased,  the  amount  of  porcelain  may  be  increased.  Thus,  if  our  work 
be  properly  constructed,  less  gold  and  more  porcelain  may  be  safely  and  success- 
fully used,  and  the  suggestions  which  I  have  to  offer  you  along  these  lines  are  based 
entirely  upon  the  theme  of  more  porcelain  and  less  gold  with  equal  and  adequate 
strength. 

Such  manifestly  desirable  advantages  are  now  to  be  obtained  by  means  of  a 
skilful  application  of  the  casting  process,  combined  with  a  more  general  use  of 
all-porcelain  teeth  instead  of  the  ordinary  thin  facings. 

You  will  probably  agree  with  me  that  this  type  of  tooth  is  preferable  for  single 
artificial  crowns,  because  it  affords  better  form,  better  color  and  greater  strength 
than  it  is  possible  to  obtain  from  the  use  of  facings.  Also  that  an  all-porcelain 
tooth  is  better  for  bridge  work  because  the  presence  of  an  occlusal  surface  of 
porcelain  instead  of  gold,  on  any  or  all  of  the  posterior  teeth,  is  advantageous  not 
only  for  cosmetic  and  hygienic  reasons  but  for  actual  masticatory  purposes  as  well. 

These  advantages  are  so  evident  that  the  more  esthetic  operator  has  been 
forced  to  look  and  hope  for  some  form  of  tooth,  and  some  method  of  application 
which  would  eliminate  the  inherent  weakness  of  thin  facings,  and  the  objectionable 
features  incident  to  their  use. 

To  overcome  the  shortcomings  of  the  so-called  "Richmond"  crown,  and  of 
the  ordinary  bicuspid  and  molar  dummy  with  porcelain  facing  and  gold  cusps, 
the  advantages  of  some  form  of  interchangeable  or  replaceable  all-porcelain  tooth, 
more  closely  simulating  the  form  and  color  of  the  natural  teeth,  were  early  recog- 


26  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

nized.  As  a  result  of  this  recognition,  many  types  have  been  introduced,  but  until 
very  recently  most  of  them  have  been  of  the  thin  facing  variety,  and  applicable 
to  the  anterior  teeth  only. 

While  the  all-porcelain  teeth,  such  as  the  Davis,  Logan  and  Justi  crowns, 
have  always  been  recognized  as  being  the  nearest  approach  to  an  ideal  substitute 
for  the  natural  teeth,  yet  they  were  not  originally  designed  to  meet  the  present 
requirements  of  crown  and  bridge  work,  and  hence  their  use  has  been  confined 
to  that  class  of  cases  where  more  or  less  temporary  results  were  all  that  was  ex- 
pected or  demanded. 

If  the  esthetic  and  hygienic  advantages  possessed  by  this  type  of  tooth, 
however,  could  be  combined  with  those  of  exact  adaptation,  and  uniform  and 
adequate  strength,  and  if  to  these  might  be  added  the  further  advantages  of  being 
cemented  to  the  structure  instead  of  soldered,  and  of  being  replaceable  and  more 
or  less  interchangeable,  it  is  evident  that  our  efforts  would  be  a  nearer  approach 
to  the  ideal. 

In  my  opinion,  which  has  been  often  expressed,  the  attachment  of  porcelain 
teeth  or  even  facings  to  the  metal  structure  by  means  of  soldering,  or  of  direct 
casting,  is  wrong.  It  is  a  wrong  principle  because  the  porcelain  is  subjected  to  a 
degree  of  heat  which  must  endanger  its  structural  integrity  and  influence  the 
preservation  of  its  color;  because  the  tooth  or  facing  is  thus  attached  in  a  stiff  and 
rigid  manner,  and,  being  friable,  is  more  likely  to  fracture  under  the  stress  of  masti- 
cation; and  because,  in  the  event  of  accident,  no  favorable  opportunity  for  repair 
or  replacement  is  usually  afforded. 

I  think  you  will  also  agree  with  me,  therefore,  that  the  elimination  of  these 
objectionable  features  must  necessarily  constitute  an  improvement,  and  that  such 
an  improvement  is  to  be  obtained  by  the  use  of  replaceable  teeth  attached  to  the 
supporting  metal  structure  only  by  means  of  cementation. 

An  experience  of  many  j^ears  has  proven  that  this  means  of  attachment  is 
reliable  in  proportion  as  the  adaptation  of  the  metal  to  the  porcelain  may  be  close 
and  accurate,  or,  in  other  words,  in  proportion  as  the  porcelain  may  be  "boxed 
up,"  protected  and  supported.  It  is  stronger  when  so  attached  because  it  is  not 
subjected  to  any  degree  of  heat,  and  is  not  held  so  rigidly,  due  to  the  cushion-like 
effect  afforded  by  cement;  and  because,  not  being  held  so  rigidly,  it  is  less  likely 
to  become  fractured.  Furthermore,  the  color  is  never  changed;  those  dark  blue 
marginal  outlines  due  to  the  penetration  of  saliva  between  backing  and  facing  are 
absent,  and  opportunity  and  facility  for  replacement  in  the  event  of  accident 
always  presents. 

As  I  have  previously  stated,  these  possibilities  and  advantages  are  to  be 
adequately  obtained  only  in  some  form  or  type  of  tooth  which  presents  as  much 
porcelain  as  possible,  which  porcelain  is  not  weakened  by  the  presence  of  metal 
pins  nor  by  the  provisions  for  retention,  and  which,  therefore,  possesses  a  maximum 
of  strength;  which  is  of  natural  form,  more  or  less  universally  applicable,  and  which 
will  need  but  a  minimum  of  grinding  for  effecting  the  desired  and  required  adap- 
tation. 

This  latter  feature,  as  applied  to  the  retentive  surface,  is  essential,  because 
in  proportion  as  a  given  form  of  porcelain  tooth  will  require  but  little  or  no  grind- 
ing upon  this  surface  in  effecting  its  adaptation  to  the  requirements  of  the  individual 
case,  may  it  be  expected  to  be  replaceable  or  interchangeable. 

These  combined  advantages,  I  believe,  are  to  be  obtained  in  a  form  of  tooth 


CASTING  PROCESS  APPLIED  TO  CROWN  AND  BRIDGEWORK        27 

suggested  by  your  essayist,  and  now  known  as  the  "Goslee  Interchangeable 
Crown  and  Bridge  Tooth,"  (Fig.  1)  to  which  I  am  pleased  to  call  your  attention. 

It  will  be  observed  that  these  teeth  as  now  made  are  of  natural  form;  that  they 
possess  the  splendid  strength  and  color  characteristic  of  the  Consolidated  tooth 
bodies;  that  they  are  adapted  to  single  crown  work  where  any  form  of  metal  base 
is  used,  as  well  as  to  intermediate  teeth,  or  "dummies"  for  bridge  work;  that  they 
afford  a  minimum  display  of  gold  and  require  but  a  minimum  amount  of  grinding, 
and  that  with  a  sufficiently  large  variety  of  molds  they  should  be  almost  uni- 
versally applicable;  also,  that  they  are  strongest  where  the  greatest  strength  is  re- 
quired; and  that  they  offer  ample  opportunity  for  secure  retention  to  the  supporting 
base  or  structure. 

A  further  advantage  made  possible  by  the  use  of  replaceable  or  interchangeable 
teeth,  which  applies  particularly  to  especially  difficult  cases,  is  to  be  obtained 
by  making  duplicates,  and  while  it  is  true  that  any  form  of  interchangeable  tooth 


Figure  1 

is  far  less  likely  to  become  broken  from  the  stress  of  mastication,  yet  the  making 
of  duplicates  coincidentally  with  the  initial  construction  requires  but  little  time,  is 
always  a  source  of  inestimable  protection  to  the  particular  patient,  and  affords 
unlimited  relief  and  satisfaction  to  the  dentist.  It  is,  therefore,  a  safeguard  which 
might  be  observed  often  and  profitably  by  everyone  whose  necessarily  small  fees 
do  not  render  it  prohibitive. 

In  all  instances,  however,  whether  duplicates  are  made  or  not,  the  color 
number  and  mold  number  of  each  tooth  used  in  every  case  should  be  recorded  on 
the  card  or  ledger  sheet,  and  thus  made  a  permanent  part  of  the  record.  Because 
of  these  advantages  and  for  these  various  reasons  I  firmly  believe  that  only  some 
form  of  interchangeable  tooth  should  ever  he  used  in  single  crowns,  or  "fixed" 
bridge  work,  of  any  type,  if  the  best  results  and  highest  possibilities  are  to  be 
attained  in  our  efforts. 

In  addition  to  such  desirable  improvements  as  may  be  achieved  by  the  use  of 
teeth  of  this  character,  the  introduction  and  application  of  the  casting  process  has 
placed  this  field  of  our  effort  upon  a  more  systematic  and  practical  basis,  as  an 
evidence  of  which  permit  me  to  call  your  attention  to  the  methods  which  I  am  now 
generally  employing,  almost  to  the  complete  exclusion  of  all  other  and  former 
procedures. 

SINGLE    CROWNS 

For  the  ten  or  twelve  anterior  teeth,  or  all  teeth  within  the  range  of  vision, 
where   porcelain   is   demanded,    the   all-porcelain   replaceable   or   interchangeable 


28  PRACTICAL   MANUAL   OF    DENTAL    CAST  INC 

crown,  with  cast  base,  and  with  or  without  a  band,  as  the  requirements  may 
indicate,  is  used  in  a  very  large  percentage  of  cases.  It  is  undoubtedly  the 
strongest,  most  artistic,  and  most  universally  applicable  type  of  substitute  for 
the  natural  tooth,  and  in  all  respects  is  second  only  to  a  skilfully  adapted  "jacket " 
crown.  Indeed,  for  the  average  dentist  it  is  better,  more  quickly  and  easily 
made,  and,  moreover,  it  possesses  an  advantage  over  the  latter  in  that  immediate 
replacement,  in  the  event  of  a  mishap,  is  possible. 

PORCELAIN  CROWNS  WITH  CAST  BASE 

In  the  construction  of  this  type  of  crown  much  difficulty  has  heretofore  been 
encountered  in  molding  the  wax  to  a  close  adaptation  to  both  the  root-end,  par- 
ticularly at  the  periphery,  and  the  base  of  the  crown,  and  in  holding  the  dowel  or 
dowels  in  the  proper  position  to  insure  correct  alignment. 

These  essential  features  have  usually  been  so  uncertain,  and  in  some  instances 
so  difficult  and  so  unsatisfactory,  as  to  cause  me  to  work  out  and  suggest  a  technique 
which  eliminates  such  uncertainty,  which  insures  accuracy,  which  is  applicable 
alike  to  all  cases,  whether  a  band  is  required  or  not,  which  relieves  the  patient  of  any 
discomfiture  whatever,  and  which  has  proven  the  most  satisfactory  method  of 
crown  construction  I  have  ever  followed. 

In  the  various  methods  now  generally  used  and  advocated,  good,  accurate, 
reliable  results  are  difficult  to  obtain,  because  the  very  plasticity  of  wax  of  any 
kind  makes  it  possess  a  tendency  to  spread  when  subjected  to  the  pressure  neces- 
sary to  mold  it  to  a  close  adaptation.  This  tendency  is  best  and  most  easily  over- 
come by  first  adapting  38  gauge  pure  gold  to  the  root-end,  which  may  be  done 
either  by  swaging  or  burnishing,  and  then  adjusting  the  dowel,  tacking  it  to  the 
base  with  solder,  and  subsequently  molding  the  wax  to  both  base  and  tooth  and 
casting  directly  to  this  disc  of  pure  gold.  If  carefully  done,  the  surface  thus 
obtained  will  always  be  a  closer  fit  to  the  root-end  than  can  be  obtained  from  the 
molding  of  wax  alone  with  any  investment  material  now  procurable,  and  will 
require  no  finishing  whatever  after  casting. 

Such  a  procedure  also  reduces  to  a  minimum  the  possibility  of  any  change 
of  form  which  may  result  from  the  warpage  or  shrinkage  of  the  gold  or  alloy  used 
in  casting,  but  to  obtain  the  best  results  necessarily  involves  the  impression  and 
die  method,  as  illustrated  in  Fig.  2,  and  explained  in  detail  in  the  Dental  Cosmos, 
August,  1911. 

The  entire  process  requires  but  little  time,  is  simple,  insures  a  more  or  less 
perfectly  adapted  base,  and  one  which  is  obtained  without  the  slightest  discom- 
fiture to  the  patient,  which  is  not  possible  when  burnishing  directly  to  the  root-end 
is  attempted.  For  single  crowns  a  slight  lingual  lip  or  band  is  usually  all  that  will 
be  required.  This  strengthens  the  attachment  between  crown  and  root,  and 
precludes  the  possibility  of  subsequent  fracture  of  the  root — for  which  purposes  a 
band  is  usually  used,  but  in  all  cases  where  the  crown  is  to  be  used  as  a  bridge 
abutment  a  full  band  should  remain. 

The  construction  of  a  crown  by  this  method  usually  involves  but  three  short 
sittings,  and  the  best  results  are  to  be  obtained  by  doing  all  the  work  directly 
in  the  mouth.  At  the  first  sitting  the  root  is  prepared,  the  root  impression  taken 
the  mold  number  and  color  selected,  and  a  temporary  crown  mounted.  This 
latter  feature  is  desirable  as  a  means  of  packing  the  soft  tissues  away  to  afford  and 
insure  a  free  exposure  of  the  root-end  at  the  next  sitting,  as  well  as  to  relieve  the 


CASTING  PROCESS  APPLIED  TO  CROWN  AND  BRIDGEUORK        29 

patient  of  the  temporary  embarrassment.  The  amalgam  die  having  been  made 
and  the  pure  gold  disc  swaged  and  tooth  selected,  in  the  meantime,  at  the  second 
sitting  the  cap  is  fitted  to  the  root,  the  dowel  and  tooth  adjusted  to  the  require- 


Figure  2 


ments,  the  dowel  then  soldered  to  the  cap,  and  the  relation  between  the  tooth  and 
cap  secured  with  casting  wax.  The  crown  is  then  cast,  the  tooth  cemented  to 
place  and  finished,  and  the  final  mounting  is  made  at  the  third  sitting. 


30  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

GOLD   CROWNS 

For  second  and  third  molars — and  even  first  molars,  when  the  presence  of 
gold  is  not  objectionable — the  cast  gold  crown  affords  results  far  in  advance  of 
anything  heretofore  obtained.  In  the  construction  of  gold  crowns  by  the  casting 
process,  however,  the  fit  or  peripheral  adaptation  is,  because  of  the  spreading 
tendency  of  the  wax,  always  best  obtained  by  previously  fitting  some  form  of 
band  to  the  root  and  then  casting  directly  to  it. 

Technique — Whenever  it  is  desirable  to  exaggerate  the  contour,  a  narrow 
band  of  platinum  or  22  karat  gold,  of  about  30  or  32  gauge,  should  first  be  made  to 
fit  snugly  around  the  entire  periphery  and  then  trimmed  to  evenly  approximate 
the  end  of  the  root,  after  which  all  of  the  contouring  may  be  done  in  wax,  which 
can  be  best  done,  perhaps,  on  a  model. 

When  an  exaggerated  contour  is  not  required,  however,  and  one  seldom  is, 
the  band  may  be  made  of  28  gauge,  22  karat  gold,  and  fitted  and  contoured  in  the 
usual  manner.  When  in  position  en  the  root,  casting  wax  is  then  molded  to  the 
end  of  the  root  inside  of  the  band,  and  this  procedure  followed  by  an  imprint  in 
the  wax  of  the  opposing  ceeth  in  all  the  movements  of  mastication. 

After  the  band  has  been  removed,  its  interior  should  be  filled  at  once  with 
casting  investment  material  and  the  occlusal  surface  properly  carved,  after  which 
it  may  be  invested  and  cast,  using  for  the  casting  the  same  grade  of  gold  of  which 


Figure  3 

the  band  was  made  (Fig.  3).  If  the  band  is  thoroughly  clean  before  investing, 
and  the  gold  to  be  cast  is  of  good  quality  and  highly  fused  before  casting,  a  good 
physical  union  will  usually  result,  but  if  it  does  not,  a  small  bit  of  22  karat  solder 
will  insure  the  same. 

These  two  general  types  of  crowns  will  meet  the  requirements  of  single  crown 
work  in  a  very  large  majority  of  cases,  and  the  results  by  either  method  are  far 
more  accurate  than  by  any  of  our  former  methods. 

FIXED   BRIDGE    WORK 

In  fixed  bridge  work,  which  constitutes  an  assemblage  of  attachments  and 
intermediate  dummies,  our  work  may  also  be  simplified,  because  three  general 
types  of  attachments  and  three  general  types  of  dummies  will  be  found  to  meet 
the  requirements  in  an  exceedingly  large  percentage  of  cases. 

Attachments — The  methods  of  obtaining  attachment  to  the  supporting  teeth 
or  roots  embrace  the  porcelain  replaceable  crown  with  dowel  and  cast  base,  the 
construction  of  which  has  just  been  referred  to,  as  applied  to  the  roots  of  anterior 
teeth,  or  when  it  is  impossible  or  inadvisable  to  preserve  the  natural  crown;  the 
inlay,  when  the  attachment  is  to  be  made  to  the  crown  of  a  natural  tooth,  which  is 
good  practice  when  the  remaining  natural  crown  is  sufifiriently  strong,  and  the  gold 
crown  for  the  molar  teeth  when  the  use  of  an  inlay  is  for  any  reason  not  indicated, 


CA  STING  PROCESS  A  P PLIED  TO  CRO IVN  A  ND  BRIDGE  WORK        ;j  1 


As  previously  emphasized,  wherever  a  dowel  crown  is  to  serve  as  an  attach- 
ment for  bridge  work,  a  narrow  band  should  always  be  used.  In  my  opinion,  this 
is  absolutely  essential,  because  of  the  additional  strain  to  which  the  root  is  to  be 
subjected,  and  as  a  means  of  insuring  permanency  and  precluding  fracture. 

When  an  inlay  is  to  serve  as  an  attachment  the  cavity  preparation  is,  of 
course,  exceedingly  important,,  and  some  form  of  post  or  posts  should  always  be 
used  to  insure  stability  and  as  a  provision  against  the  inlay  becoming  loosened 
by  the  strain  and  possible  torsion  to  which  it  is  to  be  subjected. 

The  general  applicability  of  the  inlay  as  an  attachment  for  bridge  work  has 
been  a  subject  of  considerable  discussion  ever  since  casting  became  an  accepted 
practice.  That  it  will  serve  the  purpose  as  well  as,  and  in  some  respects  even  better 
than,  a  full  crown  there  can  be  no  doubt,  providing  its  adaptation  and  stability 
are  insured. 

The  former  depends  first,  upon  adequate  and  proper  cavity  preparation, 
and  then  careful  technique  in  making  the  inlay;  and  the  latter  depends  upon  the 
use  of  a  proper  alloy  in  casting,  and  upon  pins  or  posts  of  some  form,  for  the 
reasons  mentioned. 


Figure  4 

Wherever  the  walls  of  the  supporting  tooth  are  sufficiently  strong  to  insure 
permanency;  whenever  a  suitable  cavity  may  be  properly  prepared,  the  inlay, 
well-seated  and  securely  anchored,  and  made  of  a  hard  alloy,  such  as  five  per  cent, 
platinum  in  pure  gold,  coin  gold,  or  22-karat  gold,  I  am  of  the  impression  that  such 
an  attachment  is  often  better  than  a  full  crown  because  of  the  absence  of  any 
possibility  of  gingival  irritation,  such  as  is  so  often  present  where  the  latteris  used. 

The  cavity  preparation  for  such  inlays  does  not  differ  essentially  from  that 
for  a  simple  filling,  excepting  that  its  buccal,  lingual  and  cervical  margins  must  be 
so  extended  as  to  carry  the  margin  between  tooth  and  filling  beyond  any  actual 
contact  of  the  artificial  tooth  to  be  supported  by  it,  in  order  that  each  and  all  of 
these  margins  may  be  e.xposed,  for  hj'gienic  reasons.     (See  Fig.  6) 

"Dummies" — As  dummies  for  fixed  bridge  work,  three  general  types  will 
answer  the  requirements  in  all  cases. 

The  all-porcelain  replaceable  crown  and  bridge  tooth  with  cast  backing  is 
adapted  to  all  positions  in  the  arch  where  the  conditions  of  absorption  and  occlu- 
sion will  permit  their  use,  and  is  undoubtedly  the  ideal  form  of  artificial  substitute. 
Backings  for  these  teeth  should  usually  be  cast  separately,  though  they  may  be 
made  in  sections  involving  the  number  of  dummies  between  the  attachments, 
which  should  never  exceed  three,  or  possibly  four.      Better  form,  cleaned  inter- 


32 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


proximal  spaces,  and  less  display'  of  gold,  however,  are  obtained  by  making  each 
backing  separately. 

As  a  means  of  preserving  the  proper  relation  of  the  short  sustaining  post  which 
holds  the  tooth  to  the  backing,  and  of  insuring  a  smoother  surface  adaptation  of 
the  backing  to  the  porcelain  than  the  ordinary  casting  investment  materials 
afford,  in  using  this  type  of  "dummy"  a  thin  backing  of  about  38  gauge,  pure  gold 
should  be  previously  swaged  to  the  tooth,  as  indicated  in  Fig.  4,  and  the  post 
soldered  to  it.  It  is  then  always  necessary  to  allow  as  much  surplus  end  of  post 
as  possible  to  extend  beyond,  in  order  to  insure  strength  in  the  final  attachment 
of  this  essential  part  to  the  completed  backing. 


Figure  5 

Casting  wax  may  then  be  molded  to  the  required  form,  and  the  casting  made 
directly  upon  and  against  the  thin  gold  backing,  by  which  method  any  distortion 
or  possible  misfit  due  to  shrinkage  or  warpage  is  overcome,  and  the  most  finished, 
accurate,  and  reliable  results  are  insured. 

In  the  use  of  this  type  of  tooth  in  all  cases  in  the  upper  arch  where  complete 
absorption  has  already  taken  place,  the  most  sanitary  form  of  structure  is  usually 
to  be  obtained  by  molding  the  wax  so  as  to  restore  or  approximately  follow  the 
lingual  form  of  the  tooth,  but  tapering  down  to  a  narrow  saddle  at  the  point  of 
contact  with  the  soft  tissue.  As  a  rule,  and  contrary  to  the  opinions  of  some, 
however,  wherever  the  adaptation  is  good,  such  a  type  of  construction  will  be  found 
to  be  far  more  sanitary  than  the  usual  recesses,  shelves,  and  pockets,  so  common 
in  the  ordinary  methods. 

In  the  formation  of  this  type  of  saddle,  the  desired  results  may  be  best  ob- 
tained by  first  burnishing  the  same  thickness  of  pure  gold  to  the  model,  between 
the  finished  abutments  in  position  thereon,  and  then  trimming  it  to  conform  to 


CA  .STING  PROCESS  A  P PLIED  TO  CRO  WN  A  NO  BRIDGE  WORK        IV.i 

the  size  of  the  necks  of  the  teeth  to  be  supported  by  it.  The  general  form  of  the 
structure  may  then  be  made  by  filling  in  between  this  saddle  and  the  backings 
with  wax,  after  which  the  piece  may  be  invested  and  cast.  Or  in  instances  where 
this  space  is  exceedingly  small  it  may  be  filled  with  solder. 

In  this  more  or  less  typical  fixture  (Fig.  5),  it  will  be  observed  that  practically 
no  gold  is  displayed  anterior  to  the  second  molar,  and  yet  that  a  maximum  of 
strength  presentfa  throughout. 

In  cases  where  complete  absorption  has  not  occurred,  a  saddle  is,  of  course, 
contraindicated,  but  in  these  cases  the  neck  of  the  porcelain  tooth  should  accu- 
rately fit  and  should  bear  firmly  upon  the  soft  tissue, and  the  lingual  surface  of  the 
backing  should  then  be  so  formed  as  to  be  as  nearly  convex  or  self-cleansing  as 
possible. 

For  those  cases  in  the  anterior  region  where  abnormalities  of  occlusion  or 
elongation  of  the  opposing  natural  teeth  demand  a  thin  facing,  the  ordinary  type 
of  long  pin  facing  may  be  used.  In  its  use,  however,  the  best  results  are  to  be 
obtained  by  previously  backing  it  up  with  thin  pure  gold,  adding  wax  to  this  to 
the  desired  form,  removing  the  facing  and  casting.  The  pins  may  then  be  threaded 
and,  when  the  backings  have  been  assembled  with  solder,  the  facings  may  be 
cemented  to  position,  thus  obtaining  all  of  the  previously  mentioned  advantages 
of  cementation,  combined  with  better  form  and  more  uniform  strength. 

In  addition  to  these,  for  those  cases  particularly  in  the  lower  arch,  and  in 
exceedingly  "close-bites,"  where  cosmetics  is  not  a  factor,  or  where  the  extent  of 
absorption  or  the  elongation  of  opposing  teeth  precludes  the  use  of  porcelain  in 
any  form,  the  all-gold,  cast  dummy  may  be  used.  Such  dummies  may  be  made  to 
conform  to  the  requirements  of  occlusion,  adaptation  to  gum — if  such  is  required 
• — and  contact  with  the  attachments,  in  wax,  and  then  invested  and  cast  in  one 
piece.  This  type  of  "dummy"  is  useful  in  supplying  the  lower  second  bicuspids 
and  first  and  second  molars  and  may  include  only  the  occlusal  surface,  thus 
forming  the  so-called  "self-cleansing"  type  of  bridge,  or  the  entire  tooth  with  or 
without  a  saddle,  as  the  requirements  may  be.  The  former  tj-pe  of  construction 
is  indicated  only  where  there  is  an  excessive  degree  of  absorption,  which  will 
permit  of  sufficient  space  between  the  gum  and  occlusal  surface  to  insure  self- 
cleansing  properties,  and  wherever  this  space  is  not  great  enough  to  be  easily  kept 
clean,  direct  contact  with  the  gum  will  afford  a  more  hygienic  result.  In  other 
words,  there  should  be  plenty  of  space,  or  none  at  all.  A  typical  case  of  this  kind 
showing  the  use  of  all-porcelain  dummies  in  connection  with  inlays  is  illustrated 
in  another  model. 

With  these,  the  problem  of  attachments  and  of  intermediate  dummies  for 
almost  universal  application  is  simplified  and  systematized. 

The  remaining  feature  incident  to  the  construction  of  all  forms  of  fixed  bridge 
work  involves  only  the  proper  assemblage  of  the  various  parts.  While  some  are 
casting  all  attachments  and  backings  with  an  alloy  of  five  per  cent,  of  platinum  in 
pure  gold,  and  subsequently  assembling  them  with  pure  gold,  thus  using  no  solder 
whatever,  still  a  good  grade  of  22-karat  gold  or  coin  gold  may  be  used  with  equally 
good  results.  When  either  of  the  latter  is  used,  the  final  assemblage  may  be 
effected  with  22-karat  solder,  and  providing  there  is  absolute  contact  between  all 
of  the  parts  to  be  united,  the  procedure  is  thus  somewhat  facilitated,  and  the 
results  are  uniformly  good. 


34 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


REMOVABLE    BRIDGE    WORK 

The  same  general'  ideas  are  also  applicable  to  the  construction  of  removable 
fixtures. 

For  this  class  of  work,  also,  three  general  types  of  anchorage  to  the  supporting 
teeth  or  roots  will  be  found  to  adequately  meet  the  requirements  of  the  average 
case.  These  embrace  clasps,  the  telescoping  tube  and  split  post,  and  the  various 
forms  of  manufactured  attachments. 


Figure  6-A 

Wide  clasps  encompassing  three  angles  of  the  tooth,  provided  with  an  occlusal 
rest,  not  cast,  but  made  of  heavy  rolled  clasp-metal  alloy,  probably  afford  the  very 
best  means  of  obtaining  anchorage  to  the  natural  or  artificial  crowns  of  bicuspids 
and  molars. 

That  clasps  should  not  be  cast  is  especially  emphasized,  because  the  molecular 
rearrangement  resulting  from  casting  most  of  our  present  alloys  destroys  to  a 
greater  or  less  extent  the  very  qualities  of  strength  and  resilience  demanded  of 
them,  and  which  undoubtedly  obtain  best  in  a  rolled  or  drawn  metal  or  alloy. 


CASTING  PROCESS  A  P  PLIED  TO  CRO  WN  A  ND  BRIDGE  WORK        35 


I'imjre  ()-B 


36  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

In  all  forms  of  removable  bridge  work  or  partial  dentures,  where  clasps  are 
used,  however,  some  form  of  occlusal  rest  is  necessary  as  a  means  of  providing 
against  subsequent  settlement  of  the  case.  If  this  precaution  is  not  observed, 
complete  loss,  of  occlusion  and  usefulness  will  soon  follow. 

The  telescoping  tube  and  split-post  attachment  Is  also  useful  when  confined 
to  the  roots  of  the  six  anterior  teeth. 

The  Roach,  Morgan,  Gilmore  and  other  types  of  manufactured  attachments 
will  also  be  found  valuable  when  used  in  connection  with  either  porcelain  or  gold 
crowns  or  inlays  on  the  cuspids  and  bicuspids. 

When  the  type  or  types  of  attachment  thought  to  be  best  indicated  have  been 
selected,  adapted,  and  completed,  the  casting  process  then  offers  splendid  oppor- 
tunity and  great  possibilities  for  the  subsequent  formation  of  the  body  of  the 
fixture,  and  in  this  connection  I  believe  that  the  successful  casting  of  large  pieces 
is  only  a  question  of  the  development  of  proper  technique. 

In  the  construction  of  cast  bases,  if  a  good  model  of  a  high  grade  investment 
material  is  obtained,  and  if  the  w^ax  base  is  carefully  formed,  made  sufficiently 
thin  and  properly  stiffened,  the  process  offers  the  same  assurance  of  accuracy  of 
adaptation  and  of  strength  as  previously  indicated,  and  the  possibilities  are  equally 
unlimited.  For  all  forms  and  sizes  of  saddles,  or  bases,  coin  gold  seems  to  be 
especially  adapted  to  cast  work,  and  to  afford  all  of  the  integral  strength  ordinarily 
demanded. 

In  the  presentation  of  much  of  this  technique,  quotations  from  former  papers 
have  been  necessary,  to  a  greater  or  less  extent,  but  the  fact  that  repetition  is  made 
to  serve  in  preference  to  changes  and  alterations  only  proves  that  I  am  still 
courageous  in  my  previous  convictions. 

As  a  final  suggestion,  permit  me  to  again  impress  upon  you  the  advantages 
of  simplifying  and  systematizing  your  methods,  and  of  casting;  the  necessity  for 
careful  technique  and  the  unlimited  possibilities  resulting  therefrom. 


CAVITY  PREPARATION  FOR  CAST  GOLD  INLAYS 

By  Thomas  P.  Hinman,  D.D.S.,  Atlanta,  Ga. 

In  reading  the  literature  on  the  subject  of  cavit}'  preparation  for  cast  gold  inlays, 
I  find  that  very  little  attention  seems  to  have  been  paid  to  this  most  important 
subject.  Operators  who  had  been  constructing  gold  inlays  by  the  gold  or  platinum 
matrix  method  previous  to  the  announcement  of  the  Taggart  inlay  have  evidently 
been  using  praccicallj'  the  same  method  of  cavity  preparation  for  the  Taggart  inlay 
as  they  have  been  accustomed  to  when  using  the  gold  or  platinum  matrix.  In 
making  this  statement  I  am  judging  the  mass  of  our  profession  by  those  with  whom 
I  have  had  discussions  along  this  line. 

In  using  the  metal  matrix  all  that  was  necessary  to  avoid  in  cavity  preparation 
was  undercuts,  for  it  is  obvious  that  if  the  matrix  could  be  removed  from  the  cavity 
without  distortion,  it  could  be  filled  with  solder  and  returned  to  the  cavity  and  would 
seat  as  perfectly  as  before.  This,  however,  I  have  found,  is  not  true  of  the  inlay  cast 
from  a  wax  impression.     The  reason  for  this  is  that  if  the  sharp  angles  are  left  in 


I'ig.  1 

the  cavity  they  are  reproduced  in  the  mold  or  investment  and  when  the  molten  metal 
flows  over  them  it  rubs  the  investment  in  such  a  manner  as  to  round  these  sharp 
corners,  and  when  the  inlay  is  returned  to  the  cavity  it  will  not  properly  seat. 

I  have  found  that  inlays  cast  for  cavities  in  the  proximo-occlusal  surfaces  of 
the  bicuspid  when  prepared  by  the  old  method  will  lack  to  a  considerable  degree 
seating  at  the  gingival  border.  This  observation  has  been  made  by  numerous 
other  operators  and  has  been  accounted  for  to  a  considerable  extent  by  the  theory 
that  gold  shrinks  on  cooling,  but  my  observation  has  been  that  the  shrinkage  of  the 
gold  will  not  entirely  account  for  the  misfit  of  the  inla\-.  Again,  the  floor  of  the  cavity 
has  been  left  rough  and  the  inlay  will  not  seat  because  these  same  indentations  are 


38  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

not  perfectly  reproduced  in  the  casting,  as  the  very  sharp  edges  are  rubbed  off  by 
the  molten  gold  as  it  flows  into  the  mold. 

Figure  1  represents  a  cavity  in  the  occlusal  surface  of  a  lower  molar.  You  will 
note  that  all  of  the  angles  have  been  removed  from  the  cavity  margins  and  axial 
walls  and  that  the  floor  is  perfectly  smooth  and  flat.  Note  also  that  the  margins 
are  very  slightly  beveled  from  within  outward,  so  as  to  allow  a  narrow  lap  of  the 
gold  at  this  point,  preventing  the  pumping  out  of  the  cement  during  mastication. 
If  the  cavity  was  left  with  sharp  angles  where  the  fissures  cross  and  an  inlay  cast  for 
the  cavity,  it  would  not  seat  or  fit,  because  the  sharp  angles  in  the  investment  would 
not  be  reproduced  in  the  inlay  for  reasons  heretofore  stated.  This  would  not  be 
true  if  we  had  an  investment  sufficiently  hard  to  withstand  the  friction  of  the  molten 
metal. 


Fig.  3 

Figure  2  represents  a  cavity  in  the  mesio-occlusal  surfaces  of  the  bicuspid.  Note 
that  the  neck  of  the  retention  step  has  no  sharp  angles  to  be  knocked  off  by  the 
molten  metal  flowing  into  the  mold.  Note  also  that  where  the  step  joins  the  a.xial 
wall  that  the  sharp  angles  have  been  rounded  with  a  stone.  If  we  use  curves  instead 
of  angles  at  these  points  the  inlays  cast  to  fit  such  cavities  will  seat  perfectly. 

Figure  3  represents  a  compound  cavity  in  a  bicuspid  correctly  prepared.  Note 
the  sweeping  curves  and  the  absence  of  acute  angles. 

IN   GENERAL 

If  cavities  are  prepared  with  small  carborundum  stones  instead  of  burs  there  is 
less  liability  of  producing  angles  and  rough  floors,  and  inlays  cast  to  fit  cavities  thus 
prepared  have  smoother  surfaces  on  the  side  next  the  dentine. 


SHAPING  WAX  MODEL  FOR  CAST  GOLD  INLAYS 

By  C.   E.  Abbott,  D.   D.   S. 

The  following  method  is  of  great  value  in  shaping  the  wax  model:  "In  com- 
pound proximal  cavities  in  bicuspids  and  molars  I  adjust  the  medium  soft  wax  to 
approximate  contour  and  bulk;  then  I  stretch  a  strip  of  rubber  dam,  J^  inch  by  2 
inches  over  it  and  against  it,  holding  the  ends  taut  with  the  left  hand.  Pressed 
against  the  cavity  by  the  rubber  dam,  the  wax  is  easily  burnished  to  exact  proximal 
contour,  occlusal  contact,  and  smooth  surface.  I  then  remove  the  rubber  dam, 
invest  and  cast  as  usual." 


THE  CEMENT  LINE  IN  INLAYS 

By  Clarence  J.  Grieves,  D.D.S.,  Baltimore,  Md. 

Note — The  writer  respectfully  refers  all  interested  to  his  paper,  "Cemented  Inlays  or  Contact 
Fillings,  Which?"  read  before  the  Mrginia  Dental  Society,  August,  1906,  and  published  in  The  Dental 
Summary,  which  deals  with  work  on  the  first  phase  of  this  subject,  and  is  necessary  to  an  understanding 
of  his  position  in  this  article. 

The  one  leading  question  foremost  in  the  mind  of  every  operator  who  attempts 
restoration  of  destroyed  dental  tissues,  second  only  to  the  removal  of  the  destroying 
agents  and  the  destroyed  and  the  shaping  of  caval  edges,  is  whether  the  final  cavo- 
juncture  between  filling  and  enamel  will  be  lasting  mechanically  to  meet  stress,  and 
to  prevent  retention  centers  for  recurrent  caries  and  adhesive  chemically  to  prevent 
leakage  by  solution,  by  sealing  these  edges;  so  obvious  is  the  importance  of  the 
subject,  for  it  is  the  final  equation  in  the  art  of  operative  dentistry,  that  this  paper 
needs  no  further  introduction.  No  matter  what  the  method  or  filling  material 
heretofore  employed,  its  perfect  adaptation  required  cavo-surface  contact  excluding 
mouth  juices;  edge  strength  to  meet  occlusal  food  impact,  supporting  caval  enamel 
edges;  smooth  surfaces  to  prevent  re-attachment  of  gelatinous  carious  plaques; 
extension  out  into  the  embrasures  to  prevent  the  retention  of  food  and  be  cleansed 
by  the  brush  of  it  in  mastication  practiced  with  varying  results  dependent  on  the 
material,  location  of  cavity,  skill  of  the  operator,  immunity  of  the  patient,  etc.,  etc., 
we  find  all  of  these  time-honored  requirements  for  a  successful  contact  operation 
completely  reversed  by  the  advent  of  the  method  of  the  cemented  inlay  filling. 


Fig.   I  Fig.  II 

Fig.  I.  From  Nyman's  "Porcelain  Problems,"  Cosmos,  1905,  diagrammatic  section  showing  how 
washout  at  "o"  in  butt-joint  porcelain  fillings  affect  color,  "e"  and  "d"  section  of  tooth;  e'  and  d' 
filling.     Note  the  necessary  washout  at  o'-o  of  cement  c  that  filling  may  match. 

Fig.  II.  Application  of  the  same  diagram  by  writer  to  gold  inlay  lap-joint;  "a"  gold  inlay;  "b" 
section  of  tooth;  "d  "  lap-joint  from  which  there  is  little  loss  of  cement  "c." 

During  the  inlay  period  of — say  the  past  fifteen  years — long  enough  in  all 
reason  to  test  a  new  principle — we  note  a  paradox  of  both  man  and  method;  the 
same  operator  who  formerly  spent  hours  in  attempting  these  perfect  adaptations 
of  gold  foil  to  caval  walls  is  now  willing  to  leave  them,  to  a  degree,  at  least,  marginally 
open  to  the  wash  of  the  saliva;  proximally,  in  the  same  mouth  environment,  we  daily 
see  porcelain  inlays  with  cemented  joints  washed  out  exposing  enamel  margins, 
through  which  the  light  rays  pass  into  the  porcelain,  thus,  in  the  only  way  matching 
the  tooth  surfaces  which  they  restore,  lying  directly  adjacent  to  gold  foil  operations 
in  perfect  contact  with  similar  enamel  caval  margins.  Both  operations  apparently 
saving  tooth  structure,  yet  based  and  built  upon  principles  diametrically  opposed. 


40 


PRACTICAL   MANUAL  OF  DENTAL  CASTING 


can  both  of  these  methods  be  right?  Are  the  countless  daily  converts  to  the  cemented 
inlay  wrong  in  thus  forsaking  axioms  sanctioned  by  long  experience?  The  answer 
to  these  and  many  other  associated  questions  is,  we  believe,  to  be  found  in  a  study 
of  how  mechanicall^'-made  contact  on  the  one  hand  and  chemically-made  adhesive 
cemented  contact  on  the  other  will  meet  and  overcome  the  bite  stress  and  carious 
environs  of  the  human  mouth.  As  soon  as  we  depart  from  the  teachings  of  the 
forefathers,  absolute  marginal  contact  of  filling  material  and  cavity  edges,  we  find 
the  greatest  divergence  in  principle  and  method  amongst  the  inlay  "cult"  in  caring 
for  these  edges,  for  while  all  inlay  operators  insist  on  an  adhesive  cementing  media 
between  filling  and  tooth,  the}'  sharply  divide  on  the  final  cavo-surface  finish  of  the 
filling  into: 

"A,"  Fig.  I.  Butt-joint  operations,  necessary'  from  the  friability  of  the  material 
in  all  porcelain  fillings,  where  the  cementing  media  is  expected  to  wash  out  the  depth 
of  the  -ividth  of  the  joint, ^'^  that  the  filling  may  reflect  lighc  and  match;  the  cavo- 
surface  angle  is  at  right  angles,  or  90  degrees,  as  is  the  filling  surface  angle;  the 
joint  is  open  to  the  pump  of  foods  in  bite  stress  when  exposed,  and  to  cement 
solution  from  mouth  fluids.  With  the  finest  technique  these  joints  in  porcelain 
inlays  can  be  made  only  as  fine  as  the  thickness  of  the  matrix  foil  after  burnish- 
ing.    Head!  says  such  joints  are  from  13/^  to  2 1^  times  the  thickness  of  the  foil 


Fig.  III. 
writer. 


Cuts  of  filling  from  Black's  "Operative  Dentistry."     Intirsecting  lines  made  by  the 


used  (.0001  of  an  inch);  at  the  best,  they  are  as  open  as  the  size  of  the  cement 
powder  granules;  this  is  necessarily  limited  because  extremely  fine  powder  makes 
cement  set  so  rapidly  as  to  be  impractical.  Poundstone"  found  only  five  out  of 
all  the  cements  studied  with  powder  granules,  after  solttion  in  mixing  fine  enough 
to  permit  a  joint  .0001  ot  an  inch  under  25  pounds'  pressure.  The  butt-joint 
in  gold  inlays  is  subject  to  all  of  the  doubtful  variations  produced  by  contraction 
of  wax  and  metal  and  expansion  of  investing  material;  if  the  inlay  exactly  fits 
the  cavity  it  will  protrude  by  the  distance  of  the  largest  cement  powder  granules 
which  have  not  gone  down  in  the  mix. 
"  B, "  Fig.  II.,  Lap-joint  operations,  possible  always  from  the  ductility  of  the  material' 
gold  and  its  alloys,  in  all  gold  inlays,  where  the  marginial  cementing  media  is  not 
expected  to  wash  out  for  appearances;  the  cavo-surface  angle  is  anywhere  from  a 
little  less  than  90°  to  40°,  often  topping  enamel  rods  as  in  best  foil  operations; 
the  marginal  cement  is  protected  from  the  pump  and  lave  of  bite  stress  and  to  a 


12.     Nyman,  J.  E.— Porcelain  Problems. — Dental  Cosmos,  IQ03. 

1.  Head,  J. — Test  of  the  Inlay  Cement  Problem — Dental  Cosmos,  IQ05. 

2.  Poundstone,  G.  C. — Discussion  of  the  Cement   Problem   in   Inlay  Work. 
International  Congress. 


Proceedings,   Fourth 


THE  CEMENT  LINE  IN  I  NLA  YS 


41 


degree  from  mouth  fluids  by  burnishing  down  the  lap  to  the  enamel  rods,  thus 
taking  up  any  protrusion  made  by  cement  granules  in  the  cement  line  which 
does  not  face  the  impact  of  foods,  as  in  hittt-joints,  but  rather /ac<'^  directly  away 
from  it,  a  great  advantage. 

These  two  great  classes  must  be  subdivided  again  into: 
First:     Those  which  on  section  show  the  cementing  media  throughout  the  filling 
as  only  a  line  on  the  pulpal  and  axial  walls,  the  filling  seated  mechanically  in 
the  cavity. 
Second:     Those  which  on  section  show  the  cementing  media  as  a  line  only  at  the 
margins,  appearing  in  bulk  throughout  the  filling  to  ofttimes  as  much  as  one- 
third  on  the  pulpal  end  axial  walls;  the  filling  may  have  some  mechanical  re- 
tention, but  more  is  expected  of  the  cement  "en  masse"  as  a  retainer. 
All  of  these  classifications  are  absolutely  necessary,  because  of  the  vast  difference 
in  behavior  of  the  cement  line  as  between  butt' and  lap-joints  in  all  mouths;  further, 
it  was  found  early  in  these  observations,  which  were  undertaken  some  years  ago  and 
have  been  followed  up  both  in  and  out  of  the  mouth,  particularly  with  honed  sections, 
that  while  cavities  and  inlays  made  by  any  method  were  subject  as  all  operations 
should  be  to  the  rules  laid  down  by  Black,"  there  were  certain  exceptions  to  these 


Fig.   IV 
Fig.  IV.     "A"  butt-joint  in  porcelain  inlay,  and   "B"  lap-joint  in  gold  inlay  before  exposure 
to  mouth  fluids  and  bite  stress;  presented  for  comparison  with  those  showing  use  in  mouth. 

rules,  particularly  in  butt-joints,  in  the  areas  of  possible  damage  which  are  diagram- 
matically  here  shown,  and  may  be  known  as  the  vulnerable  inlay  areas,  defined  as 
follows: 

Dividing  the  proximal  surfaces,  Fig.  Ill,  of  the  incisors  and  canines  by  a  right 
line,  "a-b,"  which  arises  just  at  the  gingivus  in  the  labio-gingival  angle  and  cuts  the 
surface,  emerging  on  the  lingual  surface  midway  between  incisal  and  gingival;  by  a 
second  right  line,  "c-d,"  which  arises  at  the  gingivus  in  the  linguo-gingival  angle, 
cuts  the  surface,  emerging  on  the  labial  surface,  one-third  of  the  distance  from  the 
incisal  to  gingival;  the  proximal  surface  is  thus  divided  into  unequal  triangles  which 
may  be  termed  the  labial,  lingual,  incisal  and  gingival  triangles,  the  smallest  of 
which  is  the  lingual.  Similarly,  the  proximal  surface  of  bicuspids  and  molars.  Fig. 
Ill,  may  be  divided  by  the  line  "a-b,"  which  arises  at  the  gingivus  in  the  bucco- 
gingival  angle  and  cuts  this  surface,  emerging  a  little  gingival  to  the  linguo-occlusal 
angle,  and  by  a  second  line,  "c-d,"  which  arises  at  the  gingivus  in  the  linguo-gingival 
angle,  crossing  the  surface  to  emerge  slightly  gingival  to  the  bucco-occlusal  angle, 
thus  dividing  the  proximal  surface  into  equilateral  triangles,  respectively,  the  buccal, 
lingual,  occlusal  and  gingival. 

3.     Black,  G.  V. — Operative  Dentistry. 


42 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


The  labial  surfaces  of  incisors  and  canines  and  the  buccal  surfaces  of  bicuspids 
and  molars  may  also  be  so  divided  by  the  lines,  "a-b,"  arising  for  the  molars  and  bi- 
cuspids, Fig.  Ill,  at  the  gingivus  on  the  mesio-gingivo-buccal  angle,  crossing  the 
buccal  surface  and  emerging  at  the  disto-bucco-occlusal  angle,  crossed  by  the  line 
"c-d,"  which  arises  at  the  gingivus  in  the  disto-gingivo-buccal  angle  and  emerges 
at  the  mesio-bucco-occlusal  angle,  dividing  the  surface  into  triangles,  the  gingival, 
occlusal,  mesial  and  distal. 

For  the  incisors  and  canines.  Fig.  Ill,  the  line  "a-b,"  arises  at  the  gingivus  in  the 
mesio-gingivo-labial  angle,  crossing  the  labial  surface  to  emerge  at  the  disto  incisal 


Fig.  \' 

Fig.  V.     "A"  lingual  and  "B"  labial  view  of  a  porcelain  inlay  in  bad  mouth  environs  six  years. 

Note  the  heavy  bite  stress  shown  in  the  enamel  of  the  incisal  edges.     When  set  these  butt-joints  were 

above  the  average.     Note  the  damage  in  the  vulnerable  mechanical  areas  and  all  down  the  lingual; 

the  solution  at  the  gingivo-labial  angle  and  yet  the  washouts  were  not  deep  nor  was  recurrent  caries  noted . 

angle,  crossed  by  the  line  "c-d,"  which  arises  at  the  gingivus  on  the  disto-gingivo- 
labial  angle  and  crosses  the  labial  surface,  to  emerge  at  the  mesio-incisal  angle, 
dividing  the  labial  surface  into  triangles,  the  incisal,  gingival,  mesial  and  distal. 

It  is  obvious  that  damage  to  the  cement  line  can  come  from  two  sources,  viz., 
mechanically  from  foods  under  bite  stress,  pumping  or  laving  out  the  cement  and 


Fig.  VI  Fig    VII 

Fig.  VI.     The  lingual  view  of  a  lateral  incisor  containing  mesial  and  distal  porcelain  inlays  placed 

at  the  same  time.     The  mesial  "a"  lapped  the  adjacent  central  and  was  sheltered  from  the  bite  pump. 

Note  the  fairly  good  joint  at  "b"  after  three  years.     The  distal  inlay  "c"  was  thus  obviously  more 

exposed  to  the  bite  with  resultant  joint  damage  at  "d." 

Fig.  \'II.     Proximal  view  same  tooth,  porcelain  inlay  "c."     Note  the  very  good  cement  joint  on 

the  labial  at  "n."  The  gingival  caries  seen  in  both  these  pictures  is  due  to  rapid  recession,  is  recent, 

and  has  nothing  to  do  with  the  crown  conditions,  which  were  maintained  for  three  years. 


THE  CEMENT  LINE  IN  I  NLA  YS 


43 


joint  contents,  and  chemically  from  a  solution  of  cement  due  to  acidity  of  saliva  and 
mucus,  whether  local  or  general.  The  incisal  and  occlusal  triangles  include  the  areas 
of  damage  by  bite  stress,  and  may  be  termed  the  vulnerable  mechanical  areas;  where 
the  lines  arise  in  the  labio-bucco  and  linguo-gingival  angles  and  the  incisal  half  of  the 
gingival  triangle  are  the  most  dangerous  to  the  cement  line  from  local  acidity  and 
may  be  termed  the  vulnerable  chemical  areas. 

Certain  areas  in  normal  mouths  appear  more  immune  than  others  to  cement 
solution,  as  the  labial,  buccal  and  small  lingual  triangles  and  particularly  the  lower 
half  of  the  gingival  triangle,  which  is  sheltered  b}'  a  healthy  gingivus,  of  which  morj 
will  be  said  later,  for,  indeed,  it  is  the  only  shelter  for  this  line  where  there  is  general 
mouth  acidity. 

The  application  of  these  lines  should  not  be  made  too  literally,  and  they  cannot 
be  drawn  "hard  and  fast,"  as  they  are  subject  to  change  in  inter-proximal  contact, 


rP 

cb               I 

^  n 

^a 

^^^J!k^ '^^Hi^.  H^^^Hi 

3 

\ 

irt 

Fig.  VIII 

Fig.  VIII.  Showing  a  large  mesio-occlusal  porcelain  contour;  superior  first  bicuspid  at  "a," 
which  fortunately  split  in  attempting  an  occlusal  section  through  it.  and  a  disto-occlusal  amalgam 
filling  at  "b;"  "c"  represents  the  cut  occlusal  portion  of  the  buccal  enamel;  "d"  the  cavo-surface 
enamel  parted  from  "a"  and  containing  some  cement;  "e"  the  darkly  stained  wall  from  "b"  amalgam 
fillin;.  Note  the  washout  on  cement  line  being  greater  on  the  bucco-occlusal  at  "n"  than  the  solution 
at  the  bucco-gingiyal  angle  at  "m"  from  acidity. 

gingival  recession  and  the  curvature  of  the  embrasures  for  the  proximal,  and  lip  and 
cheek  contact  for  the  labial  and  buccal,  but  they  give  a  most  valuable  general  idea 
to  the  operator  in  cavity  preparation. 

For  instance,  if  we  take  the  classification  of  butt  and  lap-joints  and  apply  the 
rules  of  these  areas  we  find  from  the  study  of  a  large  number  of  specimens  both  in 
and  out  of  the  mouth,  that  in: 

Butt-joints,  Fig.  IV  A,  usually  porcelain  inlaws,  after  a  period  in  the  mouth 
dependent  on  mouth  conditions  to  be  mentioned  later  for  Proximal  Cavities  in  In- 
cisors and  Canines,  just  as  the  operation  invades  the  vulnerable  mechanical  area  or 
incisal  triangle.  Figs.  \T  and  VII,  so  is  the  cement  pumped  out  sometimes  to  the 
entire  depth  of  this  triangle,  or  one-third  the  axial  walls,  Fig.  V  A;  no  matter  how 
slightly  the  joint  is  exposed  in  the  area  to  the  lingual  there  is  always  loss  of  cement 
frequently  clear  through  to  the  labial  wall,  with  consequent  loss  of  cavo  surface  enamel 
and  filling  edges,  Fig.  V  B ;  there  is  one  exception  in  these  areas  where  large  restorations, 
as  the  whole  incisal  third  in  canines  and  incisors  or  occlusal  third  in  bicuspids,  are 


4-1 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


made  in  porcelain;  here  butt-joints  do  well  on  the  buccal  and  lingual  in  bicuspids 
and  the  labial  in  incisors  and  canines  where  parallel  to  the  incisal  and  occlusal  sur- 
faces the  cement  line  is  sheltered  from  the  bite  pump  by  a  wall  of  porcelain  opposed 
above  it;  the  Hngually-exposed  joint  is  quickly  pumped  out  and  soon  stands  as  does 
the  enamel,  alone. 

Proximal  Cavities  in  Bicuspids  and  Molars — Here,  with  even  greater  force ,  the 
rule  for  mechanical  areas  applies  to  the  occlusal  triangle.  Fig.  VIII;  frequently  gold 
inlays  with  butt-joints  are  seen  in  this  location,  but  whether  gold  or  porcelain  we 
find  the  cement  pumped  out  down  along  the  axial  wall,  often  over  the  pulpal  wall, 
and  always  washed  entirely  from  the  bucco  and  linguo-occlusal  angles. 

Labial  cavities  jor  incisors  and  canines  in  the  incisal  triangle — The  cement  line 
does  well  except  in  erosion  mouths  (to  be  classified  later),  where  the  cave  surface 
margins  disappear  as  though  brushed  away  leaving  the  filling  "high  and  dry." 
FiR.  IX. 


AH 

c         B      "^    ^ 

B|  -     ^ni          "*"      \  <f       ^ 

b         a.       ^e 

Fig.   IX 


Fig.  X 


Fig.  IX.  Lateral  incisor,  large  porcelain  inlay  at  "a,"  time  in  the  mouth  about  five  years;  co- 
hesive gold  filling  at  "b''  placed  some  years  before  porcelain;  stained  with  eosin,  cut  to  section  line 
x-y  and  honed;  mouth  of  the  erosion  type. 

Fig.  X.  Section  cut  at  x-y  retained  in  cement  "a."  Porcelain  inlay  section  at  "c,"  enamel  and 
dentine  at  "b,"  gold  filling  section  at  "d;"  dark  area,  stained  cement  at  "e."  Note  the  depth  of 
washout  at  "g"  and  leakage  and  recurrent  caries  at  "h." 

Bicuspids  and  molars — In  the  occlusal  triangle  the  line  suffers  from  bite  stress 
just  in  proportion  as  the  inlay  invades  that  triangle,  and  as  the  tooth,  particularly 
the  inferior,  tilts  to  the  occlusal,  Fig.  III. 

Caries  can  and  does  recur  after  this  laving  process.  Fig.  X,  when  shelter  is 
afforded  for  attachment  of  plaques,  deep  under  the  caval  walls;  the  rule  being  that 
when  the  cement  has  laved  below  the  depth  of  the  enamel  rods  in  mouths  prone  to 
caries,  it  begins  at  any  shelter  on  the  axial  dentine. 

Butt-joints — In  the  vulnerable  chemical  areas  named,  the  labio-bucco  and 
linguo-gingival  angles  and  the  upper  half  of  the  gingival  triangle,  or,  in  other  words, 
in  the  usual  retention  centers  dangerous  to  all  contact  operations,  the  cement  line 
suffers.  Fig.  XI,  from  recurrent  caries  every  time  a  chemical  solution  of  cement 
occurs  to  the  depth  of  the  enamel.  Fig.  XII,  but  the  percentage  of  its  occurrence  to 
any  great  depth  is  much  smaller  than  the  "wash-outs"  in  the  vulnerable  mechanical 


THE  CEMIiNT  LINE  IN  INLA  YS 


45 


areas,  just  as  the  percentage  of  recurring  decay  is  very  much  less  for  inia>s  than  for 
contact  operations  in  these  dangerous  areas,  F"ig.  XIII;  this  we  may  account  for  later 
dependent  upon  a  number  of  modifying  factors,  local  and  general. 

This  is  just  where  the  variation  for  inlays  previously  mentioned  comes  in, 
from  the  rules  of  Black,  for  contact  operations;  due  to  this  fact  it  is  here  laid  down  as 
a  rule  that  in  butt-joints,  or,  in  other  words,  porcelain  inlays,  for  no  judicious  operator 


Fig.  XI 


Fig.  XII 


Fig.  XI.  Small  disto-proximal  filling  left  superior  canine  stained  with  epsin;  in  use  twelve  years; 
"a"  enamel,  "b"  porcelain  filling.  Note  that  the  same  drying  crack  "c,"  which  split  the  enamel  after 
excision,  continues  on  through  the  filling,  and  the  filling  is  well  retained,  notwithstanding  the  ugly 
washouts  at  "d." 

Fig.  XII.  A  section  cut  out  of  same  tooth  and  filling  on  through  the  labial  at  "a"  to  show  the 
state  of  the  caval  cement,  which  is  good  at  "b,"  and  the  dangerous  looking  washout  shown  at  "d," 
Fig.  XI,  are  of  little  depth,  the  eosin  stain  having  gone  only  as  far  as  "c." 

would  use  a  butt  if  he  could  make  a  lap-joint,  the  cement  line  should  not  be  extended 
any  further  out  into  the  embrasures  proximally,  and  particularly  not  extended  into 
the  incisal  and  occlusal  triangles,  than  is  absolutely  necessary  for  removal  of  damaged 
tooth  structures;  in  other  words,  the  butt-joint  operation  should  be  "extended  to 


Fig.  XIII 
Fig.  XIII      Section  without  staining  cut  through  proximal  porcelain  filling,  lateral  incisor;  time 
in  mouth,  1,3  years;  "e"  enamel,  "d"  dentine,  "r"  pulp  cavity,  "p"  porcelain  filling.     Note  the  per- 
fect condition  of  the  cement  at  "c,"  notwithstanding  the  open  washouts  at  "a"  in  the  butt-joint, 
which  has  undoubtedly  been  protected  by  the  contained  film. 

prevent"  as  little  as  possible,  Fig.X'lII,  as  there  is  more  danger  from  the  mechanical 
areas  named  in  "pump  out"  of  cement.  Fig.  V,  than  in  the  chemical  areas  named 
from  solution  of  cement,  Figs.  VI  and  VII,  all  of  which  is  directly  opposed  to  the 
correct  rules  for  contact  operations. 

Mention  has  been  made  of  the  shelter  afforded  under  the  normal  gingivus,  for 
here  the  butt-joints,  as  indeed  joints  of  all  operations,  arc  at  their  liest,  and  a  word 


46 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


is  necessary  as  to  the  causes  for  that  immunity.  In  a  report  made  on  "The  Behavior 
of  Certain  Metals  in  the  Mouth,"*  the  writer  found  all  vulnerable  metals  as  gold 
alloyed  with  zinc  in  solders  and  gold-plated  german  silver,  as  "D"  bands  in  ortho- 
dontia, showing  deep  destruction  of  the  metal  just  at  and  above  the  gingival  margin 
and  perfect  conservation  of  the  metal  as  when  first  placed  below  the  gingivus;  this 
occurred  only  in  the  normal  gingivus;  any  irritation  from  fitting  the  band  interfered 
with  this  function,  when  the  metal  was  quite  as  much  eroded  as  that  exposed  to  the 
dangerous  line  directly  above  the  margin. 

It  was  further  proven  that  vulnerable  metals,  when  in  fixed  actual,  but  not 
pressure  contact  with  the  mucosa  were  not  affected  by  the  degeneration  from  mouth 
juices,  which  quickly  attacked  them  at  exposed  parts;  this  was  shown  by  a  series 
of  experimental  bridges,  the  saddles  of  which,  made  of  vulnerable  metals,  were  placed 
in  contact  with  the  membranes  covering  the  ridges;  removed  and  examined  from  time 
to  time  it  was  found  that  they  were  clean  and  undamaged,  where  in  good  contact, 
but  the  exposed  edges  buccally  and  linguall}'  were  eroded.  It  was  reasoned  and  so 
reported,"  that  this  immunity  might  have  been  due  to  the  alkalinity  common  to  all 


Fig.  XIV.     From  Conzett's  article.  "Gold  Inlays,"  Items  oj  Interest,  to  show  ideal  lap-joint  at    'a." 
From  Black's  "Operative  Dentistry,"  wrong  lap  for  foil  operation  but  right  lap  for  gold  inlay  at  "a." 

normal  mucosa,  but  more  than  likely  it  is  an  illustration  of  the  immunity  conferred 
on  all  of  the  mouth  mucosa  by  the  constant  chemictoxis  of  the  leucocytes.  Movable 
membrane  contact  is  most  damaging  in  carious  environs,  witness  the  record  written 
on  many  buccal  surfaces  cf  permanent  molars  as  they  erupt  and  are  exposed  to  it  in 
the  child  mouth — due  to  the  retention  afforded  by  the  cover  cf  the  commissures. 
The  long  record  cf  both  butt  and  lap-jcints  in  crowns  carefully  set  without  irritation 
under  the  gingivus,  is  most  convincing;  the  cement  line  will  stand  under  the  protec- 
tion of  the  gingivus  in  the  butt-jcints  cf  comparatively  flat  copes  of  all  porcelain 
crowns  and  in  the  lap-joints  cf  banded  crowns,  the  best  cf  which  are  far  inferior  to 
the  poorest  joint  made  in  the  inlay;  this  might  be  explained,  to  a  degree,  by  the  pro- 
tection afforded  the  cement  by  crown  contour  from  bite  stress,  but  for  the  fact  that 
as  soon  as  gingival  recession  occurs,  caries  recurs  promptly  proximally,  which  is  also 
true  of  all  operations  in  this  locality  in  carious  mouths.  But  whatever  the  cause  for 
this  immunity  afforded  by  the  normal  gingivus,  all  agree  that  it  exists,  and  that  all 
operations  should  be  put  under  its  cover  without  damage  to  it,  when  possible. 

Lap-joints,  Fig.  IV  R,  when  correctly  made  with  the  metal  ductile  enough  and 
in  sufficient  bulk  to  be  well  "spun"  and  burnished  over  the  cavo  surface  angle  retain- 
ing and  protecting  the  cementing  media,  this  grinding  over  and  burnishing  doing 

4.  Grieves,  C.  J. — The  Behavior  of  Certain  Metals  in  the  Mouth.     Proceedings,  National  Dental 
Association,  1909. 

5.  Grieves,  C.  J. — A  Review  of  Bridge  Work. — Dental  Brief,  Sept.,  1910. 


THE  CEMENT  LINE  IN  INLA  YS 


47 


damage  to  but  the  finest  external  line  of  cement,  the  rest  of  which  is  protected  thereby, 
Fig.  XIV,  are  the  writer's  ideal,  and  in  his  judgment,  a  long  step  to  the  final  solution 
of  this  problem,  Fig.  XV;  after  a  long  and  careful  study  of  lap-joints  tested  side  by 
side  with  butt-joints,  often  in  the  same  filling.  Fig.  XVII,  in  both  the  mechanical 


Fig.  XV 


Fig.  XVI 


Fig.  XV.  Section  gingival  tliird  gold  inlay  disto-proximal  right  superior  central,  showing  ideal 
butt-joint  conditions;  "a"  gold  inlay;  "b"  dentine  and  cement,  "c"  butt-joint. 

Fig.  XVI.  Section  at  the  linguo-occlusal  angle  superior  first  bicuspid,  showing  successful  long 
lap  joint  of  a  gold  inlay,  mouth  environs  bad;  time,  nearly  four  years;  "a"  cross  section  of  enamel  of 
the  linguo-occlusal  angle,  "b"  lap  joint,  "c"  body  of  inlay,  "e"  cement  in  joint  complete  almost  to 
cavo-surface  angle,  "d"  investing  cement  to  retain  parts  while  honeing. 

and  chemical  areas,  they  present  conditions  which  are  most  satisfactory.  Fig.  XVII. 
There  is  little  or  no  loss  of  cement  from  the  lave  of  bite  stress,  for  the  reason  that  it  is 
sheltered  under  the  cover  of  the  properly  finished  "lap,"  hence  we  may  follow  the 
laws  of  Black  and  extend  occlusally.  Fig.  XVI,  and  into  the  embrasures;  again,  when 
the  lap  is  properly  finished — at  no  time  an  easy  thing — the  loss  of  cement  by  solution 


Fig.  XVII 

Fig.  XVII.  .A — Lingual  view  of  a  mesio-disto-occlusal  gold  inlay,  right  superior  first  molar  in 
use  six  years;  "c"  gold  inlay  surface,  "b"  caval  cement  in  good  condition  because  of  perfect  protection 
of  the  lingual  wall  by  good  lap  joints  at  "a." 

B — Caval  view  of  same  filling.  The  caval  cement  is  intact  on  the  lingual  filling  surface  at  "n"  to 
the  line  x-y  dividing  the  inlay  mesio-distally.  The  buccal  wall  was  protected  only  by  a  butt-joini-  and 
it  will  be  noted  that  all  of  the  caval  cement  buccal  to  the  line  x-v  is  either  washed  out  or  stained  at  "  m. 


48 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


in  the  dangerous  chemical  areas  is  slight,  while,  of  course,  in  these  areas,  under 
certain  mouth  conditions,  all  operations  fail,  they  stand  up  just  as  much  better  to  the 
attack  as  the  butt-joint  stands  better  than  the  contact  operation,  Figs.  XVII  and 
XVIII.  The  metal  in  the  lap-joint  must  meet  all  requirements  for  perfect  contact 
finish;  there  is  only  one  such,  in  the  opinion  of  the  writer,  and  that  is  pure  gold, 
alloying  of  which  seriously  interferes  with  marginal  adaptation,  just  as  it  does  in  foil 
operations,  Fig.  XIV;  in  fact,  one  of  the  principal  arguments  for  the  lap-joint  is  to 
be  found  in  its  perfect  protection  of  the  enamel  rods  of  the  cavo  surface  angle.  The 
failure  of  the  lap-joint  is  largely  one  of  technique,  and  occurs,  strange  to  say,  just 
where  the  butt-joint  is  at  its  best,  under  the  normal  gingivus;  a  greater  number  of 
failures  are  here  to  be  reported  than  at  any  other  point,  for  the  evident  reason 
that  the  correct  setting  and  finishing  of  the  lap  under  the  gingivus  without  damage 
thereto  or  "over- flange,"  causing  retention,  is  one  of  the  most  difficult  procedures 
in  operative  dentistry.  Fig.  XIV,  and  needs  much  betterment. i-' 

It  might  be  appropriate  in  this  connection  to  mention  the  method  applied  by 
Levi  C.  Taylor,  for  small  operations,  as  of  building  the  filling  of  gold,  usually  of  the 


Fig.  XVIII 

Fig.  XVIII.  A — Looking  into  an  occlusal  cavity  in  a  molar  filled  four  years  with  lap-joint  gold 
inlay,  of  which  a  section  has  been  cut  at  the  disto-buccal  cusp,  showing  perfect  condition  of  cement  at 
"a,"  in  fact,  through  the  whole  cavity. 

B — View  of  the  linguo  wall  of  the  inlay  which  filled  cavity  shown  in  A.  Note  the  lap  joint  which 
has  stood  heavy  morsal  stress  with  the  loss  of  but  little  cement  at  "a,"  the  rest  of  the  cement  "b"  is 
in  good  shape. 

crystal  types,  in  the  midst  of  setting  cement  to  a  moderate  lap-joint,  Fig.  XIX;  a 
number  of  such  have  been  examined,  and  they  seem  to  combine  the  advantage  of 
both  the  inlay  and  contact  operations,  also  amalgam  fillings  after  this  method  built 
of  quick-setting  alloy  in  slow-setting  cement,  Fig.  XX,  with  the  help  of  an  oiled 
matrix, finishing  to  the  least  bit  of  a  lap  of  the  cavo-surface  angle;  under  particularly 
unfavorable  mouth  conditions  these  fillings  do  well,  and  the  writer  believes  that  every 
amalgam  filling  should  be  thus  cemented  in. 

Reference  has  been  made  to  the  vulnerable  chemical  areas,  and  we  find  mouths 
where  all  areas  are  vulnerable,  in  others  chemical  solution  is  localized;  when  we  realize 
that  the  cement-line  is  continually  bathed  in  saliva,  a  fluid  constantly  changing  to 
reflect  systemic  conditions,  some  classification  of  mouth  types,  broad  and  necessarily 
defective,  though  it  may  be,  is  here  necessary,  to  a  further  study  of  the  subject. 
While  comparatively  little  is  known  of  mouth  conditions — for  instance,  caries  of  the 
enamel  is  yet  unsolved — certain  data  is  at  hand,  thanks  to  the  efforts  of  many 


13'     Lane,  J.  G,— 'A  Compg^rison  of  Differences  of  Opinion, — Denial  Brief,  Feb.,  19U, 


THE  CEMENT  LINE  IN  I  NLA  YS 


49 


authorities,  particularly  Miller,  Williams  and  Black,  Michael,  Kirk  and  Low,  and 
the  writer  presents  this  diagrammatic  scheme  with  apologies  to  these  investigators. 
We  may  divide  mouth  types  systemically  into  the  Normal,  the  Hypo-acid  and 
Hyper-acid,  as  follows: 


Scheme  of  Mouth  Types  as 

NORMAL 

MOUTHS — Can  be  kept  clean. 

SYSTEMIC  CONDITION  —  Biochemical 
changes  equally  balanced. 

SALIVA — Neutral  or  alkaline. 

MUCUS — Alkaline;  medium  in  amount  exist- 
ing independently  in  ropes  depositiuR  on 
all  surfaces. 

SULPHOCYANATES— Normal,  glycogen  and 
ammonia  little  or  none. 

CARIES — Medium  in  amount,  dark  and  slow. 

EROSION— None. 

SALIVARY  CALCULUS— Medium  at  the 
usual  point. 

SERUMAL  CALCULUS— None,  frequent  sul- 
phid  and  other  stains. 

FILMS  ON  TEETH — On  all  surfaces  e.xcept 
occlusal;  alkaline  or  acid  according  to  per- 
centage of  glycogen,  protective  e.xcept  in 
retention  centers. 

INLAYS  do  well,  and  butt-joints  stand,   but 
often  stain;  suffer  most  in  the  stress  areas, 
slightly    in    the    retention    centers.     Figs. 
V,  VI,  VII,  XI,  XII,  XIII,  XXI. 
HYPER-ACID 

SYSTEMIC  CONDITION— Oxidation  low; 
increase  in  organic  acids;  Biochemical 
changes  slow;  Arthritism,  showing  in  two 
phases.  Erosion  and  Pyorrhea. 

"A"  EROSION  MOUTHS— Which  look  "too" 
clean. 

SALIVA — Acid  from  acid  sodium  phosphates, 
clear  and  limpid. 

MUCUS — None,  that  secreted  is  in  solution. 

SULPHO  CYANATES  in  excess. 

GLYCOGEN  below  and  AMMONIA  above 
normal. 

CARIES— None. 

EROSION — In  excess  on  cheek  or  lip  contact. 

SALIVARY  AND  SERUMAL  CALCULUS— 
None,  no  sulphid  nor  other  stains. 

FILMS  ON  TEETH — A  few  growths  open  to 
the  wash  of  saliva. 

INLAYS — Look  well  but  fail,  particularly  butt- 
joints  from  all  around  solution  of  cement 


Associated  with  the  Systemic  State 

due  to  the  acid-sodium  salts;  other  opera- 
tions do  well.     Figs.  IX.  X  and  XXII. 

"B"  PYORRHEA  MOUTHS— Teeth  dirty 
cer\'ically  from  gingival  waste  and  calculi. 

SALIVA — Alkaline  from  tissue  waste. 

MUCUS — Sulpho-cyanates,  glycogen  and  am- 
monia above  the  normal. 

CARIES — Little,  considering  the  numerous  re- 
tention centers  caused  by  gingival  recession. 

EROSION— None. 

SERUMAL  AND  SALIVARY  CALCULUS— 
In  excess  and  recurring;  staining  from  all 
causes. 

FILMS  ON  TEETH— "Materia  alba."  greasy, 
alkaline. 

INLAYS  and  all  fillings  do  well  except  in 
marked  retention  centers;  butt-joints  stand 
almost  as  well  as  lap-joints,  but  stain. 

HYPO-ACID 

DIRTY  MOUTHS— Cannot  be  kept  clean. 

SYSTEMIC  CONDITION— Oxidation  high- 
decrease  in  organic  acids;  increase  in  ex- 
cretion of  saline  chlorids. 

SALIVA — Neutral  as  secreted  but  acid,  thick 
and  ropy;  odor  and  color  from  the  Mucus 
— ivhich  is  abnormal,  containing  a  high 
percentage  of  carbohydrates  as  excreted, 
highly  acid,  forming  sordes. 

SULPHO-CYANATES— .-Xud  ammonia  below 
normal. 

GLYCOGEN — Greatly  in  excess. 

CARIES — Excessive,  rapid,  white,  and  always 
recurs,  no  matter  what  the  operation. 

EROSION— None. 

SALIVARY  CALCULUS— In  excess. 

SERUMAL  CALCULUS— Occasionally,  sul- 
phid and  other  stains  in  excess. 

FILMS  ON  TEETH— A  "thick  acid  felt" 
everjvvhere;  the  ideal  media  for  B.  acidii 
lactici. 

INLAYS  WITH  LAP-JOINTS  do  better  than 
contact  operations;  butt-joints  fail  quickly, 
caries  recurs  at  all  points  on  all  operations 


While  it  is  most  desirable  that  the  individual  operator  should  ha\e  an  intimate 
knowledge  of  salivary  analysis,  so  intricate  is  the  subject  at  present  it  is  hardly  to 
be  expected  that  he  can  apply  it  to  his  daily  work;  the  foregoing  scheme  shows  the 
principal  mouth  types,  and  a  close  obser\^er  may,  by  carefully  noting  conditions, 
read  the  record  written  on  the  teeth  and  gingivus  as  a  geologist  reads  the  rock.= 
^nd  reach  a  fairly  accurate  conclusion  of  existing  mouth  conditions, 


50 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


Thus,  it  will  be  noted  from  the  foregoing,  that  caries  does  not  recur  in  the  mouths 
of  erosion  at  alt  and  rarely  in  those  of  pyorrhea  in  the  division  classed  systemically  as 
Hyper-acid,  that  for  instance,  in  the  erosion  types  there  is  a  coincident  lack  of  the 
carbohydrate  element  and  an  excess  of  sulpho  cyanates  coupled  with  an  absence  or 
rapid  solution  of  mucus,  the  saliva  is  acid  because  of  the  acid  sodium  and  calcium 
salts  secreted  as  a  content  of  the  mucus,  a  systemic  acidity. 

On  the  contrary,  in  the  mouths  classed  systemically  as  Hypo-acid,  dental 
caries  is  rampant;  here  the  carbohydrate  element  is  far  in  excess,  as  is  the  mucus, 
which  is  abnormal  in  quantity  and  quality,  being  thick  and  ropy,  with  the  sulpho- 
cyanates  coincidentally  below  normal,  the  saliva  is  again  acid  from  the  decomposi- 
tion of  the  carbohydrate  element  excreted  with  the  mucus;  a  general  bacterial  acidity. 
Lying  between  these  extremes,  and  gradually  merging  into  each,  according  to  the 
variation  in  diatheses,  is  the  normal,  where  the  body  processes,  and  consequently 
the  excreta,  through  the  saliva,  are  equally  balanced,  the  saliva  is  alkaline  or  neutral 
in  reaction,  caries  occurs,  but  does  not  recur  except  when  retention  centers  are  pro- 
duced for  the  decomposition  of  carbohydrate  foods,  producing  areas  of  local  acidity. 


Fig.  XIX 


Fig    XX 


Fig.  XIX.  A — Section  cut  through  an  occlusal  filling  of  crystal  gold  condensed  into  setting 
cement,  extracted  and  stained;  "a"  gold  filling,  "b"  cement  which  is  perfect.  Note  the  conditions 
at  the  cavo-surface  angles. 

Fig.  XX.  Similar  section  through  an  amalgam  filling  made  after  the  same  method,  same  time  in 
the  mouth,  similarly  stained;  "a"  amalgam,  "b"  cement,  owing  to  contraction  of  amalgam  stains  at 
"c",  but  no  caries. 

As  all  junctures  between  filling  and  tooth,  and  butt  and  lap-joints  are  no  ex- 
ception to  the  rule,  bear  much  the  same  relation  to  incipient  caries,  as  do  enamel 
faults  and  fissures,  often  creating  immediately  retention  centers  of  the  worst  type,  a 
better  understanding  is  needed  of  the  enamel  surfaces,  and  more  particularly  as  to 
what  actually  covers  them  to  the  dissipation  or  conservation  of  the  cement  line; 
the  writer  is  fortunate  in  being  able  to  recall  to  your  minds  these  conditions  in  words 
other  than  his  own. 

Miller''  tells  of  a  film  of  micro-organism  which  covers  the  surfaces  of  all  teeth, 
from  100  taken  at  random  out  of  1,000  teeth  in  two  different  experiments,  and 
stained  by  eosin  and  the  Gramm  method,  he  says:  "  I  was  surprised  ac  the  universal 
presence  and  extent  of  the  films;  of  the  molars  and  bicuspids,  only  the  cusps,  and 
usually  a  small  portion  of  the  buccal,  and  less  of  the  lingual  surfaces,  were  found 
free  from  films;  of  the  incisors  and  canines,  the  labial  surfaces  showed  a  film  without 
a  single  exception;  at  the  neck  of  the  tooth,  where  the  enamel  was  completely  pro- 
tected by  the  gum,  there  was  no  film.     *     *     *     Fissures,  grooves,  pits  and  depres- 

7.     Miller,  W.  D. — The  Presence  of  Bacterial  Plaques  on  the  Surfaces  of  the  Teeth  and  their  Sig- 
nificance.— Denial  Cosmos,  1902. 


THE  CEMENT  LINE  IN  INLAYS 


51 


sions  of  all  kinds  are  indicated  by  deeper  staining  and  denser  films.  I  was  curious 
to  see  how  the  teeth  of  my  colleague,  Dr.  York,  who  is  immune  to  caries,  reacted.  * 
*  *  *  on  the  whole,  Dr.  York's  teeth,  being  carefully  kept  and  highly  polished, 
show  the  film  restricted  chiefly  to  the  cervical  portions  and  proximal  surfaces." 


Fig.  XXI 

Fig.  XXI  Caval  and  lingual  views  of  a  large  porcelain  contour  in  a  normal  mouth  about  two 
years. 

A — The  gingival  seat.  Note  that  the  only  loss  of  cement  is  at  "b,"  where  the  porcelain  is  exposed 
from  solution  just  at  the  gingivus;  "a"  cement  intact. 

B — The  entire  pulpal  wall  from  x  gingival  to  y  incisal;  the  cement  "a"  is  perfectly  preserved 
except  at  "b,"  where  it  is  stained  from  exposure  due  to  pump  from  bite  stress  in  the  incisal  triangle. 
Note  the  little  solution  on  the  labial  wall  at  "c"  as  compared  to  the  deep  washout  at  "b." 

C — The  lingual  view  showing  contour,  and  loss  of  cement  shown  in  A  gingivally. 

Again  he  says,  in  answering  the  question.  Are  the  bacteria  films  or  plaques  re- 
stricted CO  carious  teeth?  "The  question  is  very  easily  answered  in  the  negative. 
They  are  not  characteristic  of  carious  teeth,  but  of  dirty  teeth  or  rather  of  teeth  whose 


Fig.  XXII 
(Compare  with  Fig.  XXI.) 

Fig.  XXII.  Caval  and  lingual  views  of  a  large  porcelain  contour  in  a  mouth  of  the  erosion  type, 
about  two  years. 

A — The  gingival  seat.  Note  the  great  loss  of  cement  at  "b"  in  the  two  gingival  angles  where 
exposed  to  acid  saliva  and  its  protection  by  the  gingivus  at  a';  the  character  of  the  caval  cement  at  a(2) 
is  not  as  good  as  in  A,  Fig.  XXI. 

B — The  entire  pulpal  wall  from  "x"  gingival  to  "y"  incisal;  the  cement  "a"  is  in  poor  shape, 
having  lost  its  retentive  value;  at  "b"  it  is  stained  for  the  same  reasons  as  in  B.  Fig.  XXI;  it  is  com- 
pletely lost  along  the  entire  labial  and  lingual  at  "c"  and  "d,"  allowing  entrance  of  light  rays,  producing 
perfect  color  but  proving  the  solvent  power  of  a  saliva  loaded  with  acid  sodium  salts. 

C — The  lingual  view  showing  contour  and  complete  loss  of  cement  from  "n"  to  "  m  "  on  the 
linguo-gingival  anple. 


52 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


surfaces  are  not  kept  perfectly  cleansed  by  either  natural  or  artificial  friction.  Teeth 
which  are  not  kept  clean  by  the  process  of  mastication;  teeth  without  antagonists; 
loose  teeth  which  oscillate  in  the  mouth,  are  covered  with  greasy  deposits  ("materia 
alba"  of  Leeuewenhoek)  show  most  abundant  growths;  in  fact,  it  would  be  very 
difficult  to  find  teeth  which  did  not  show  bacteria  adhering  to  the  surfaces  at  some 
point    or   other." 

Later  he  saj's,  ' '  We  may  put  it  down  as  an  axiom  that  films  will  be  found  wherever 
the  surfaces  of  the  teeth  are  not  kept  free  from  deposits  of  mucus,  epithelium,  food, 
etc.,"  Fig.  XXIII. 

Lastly,  in  discussing  the  existence  of  the  gelatinoid  plaque,  he  remarks:  "If  the 
food  accumulated  on  the  surfaces  or  in  the  cavity  undergoing  fermentation,  it  is 
readily  conceivable  that  a  special  growth  of  bacteria  in  immediate  contact  with 
the  surface  of  the  teeth  would  intensify  the  action  at  that  point,  though  fermentation 
itself  would  certainly  not  be  solely  dependent  on  such  growth;  if  there  is  an  accumula- 
tion of  nitrogenous  food,  or  if  the  surface  of  the  tooth  is  coated  with  a  greasy  layer  of 


A 

1 

^0- 

1 

^_ 

1 

X 

/ 

" 

-   -.  ::■  -  ^ 

m 

^m 

L 

..,„.^„,„„ 

Fig.    XXIII 

Fig.  XXIII.     From  Miller's  "The  Presence  of  Bacterial  Plaques  on  the  Surfaces  of  the  Teeth  and 
Their  Significance,"  Cosmos,  1902,  showing  that  films  may  occur  without  caries. 


mucus,  epithelium,  etc.,  there  will  be  putrid  decomposition  with  alkaline  reaction, 
which  again  may  be  most  intense  directly  on  the  surface.  In  such  cases  it  is  con- 
ceivable that  the  film  might  serve  as  a  protection  to  the  tooth."     (The  italics  are  mine.) 

You  will  note  that  Miller  describes  these  films  as  covering  all  teeth,  normal  as 
well  as  carious,  the  film  consisting  of  mucus  (to  which  Kirk,  Lohman,  etc.,  give  25% 
carbo-hydrate  and  75%  nitrogenous-moiety),  epithelial  scales,  organism,  etc.,  so 
the  decomposition  of  this  film  in  the  normal  would  be  a  nitrogenous  material,  putrid 
and  alkaline,  protective  in  all  but  the  retention  centers  for  carbo-hydrate  foods, 
which  would  then  raise  the  acidity  to  the  point  of  decalcification,  but  if  the 
percentage  of  carbo-hydrate  in  the  mucus  is  raised,  as  in  the  Hypo-acid  diathesis, 
lactic  acid  fermentation  takes  place  in  the  film  and  caries  becomes  general,  unless 
the  acid  is  diluted  by  the  entrance  of  saliva,  due  to  the  porosity  of  the  film. 

It  is  interesting  in  this  connection  to  quote  J.  Leon  Williams  on  these  films  under 
carious  condition.  He  says:  "I  have  ground  more  than  four  hundred  sections  of 
enamel  in  every  stage  of  decay  of  the  teeth — in  one  respect  every  specimen  has  shown 
precisely  the  same  appearance;  lining  cavities  or  covering  surfaces  where  decay  has 

8.     Williams,  J.  Leon. — A  Contribution  to  the  Study  of  Pathology  of  Enamel. — Denial  Cosmos,  1897 


THE  CEMENT  LINE  IN  INLA  YS 


5^ 


c(jnimenceil,  there  is  always  to  be  seen  a  tliirk  felt-like  mass  oi  aciil,  lonning  micro- 
organisms. This  mass  of  fungi  is  so  dense  and  adhesive  as  to  make  it  highly  im- 
probable that  enamel  is  affected  except  in  rare  or  special  instances  by  any  acid  other 
than  that  which  is  being  excreted  by  bacteria  at  the  very  point  where  the  enamel  is 
attacked."     Fig.  XX IV'. 

It  will  be  seen  from  the  above  that  Williams  studied  the  film  in  the  abnormal. 
He  will  not  admit  that  this  film  may  be  permeated  by  a  general  mouth  acidity  except 
"in  special  instances,"  one  of  which  we  take  to  be  erosion  types  mentioned  before, 
where  the  films  do  not  exist  at  all,  or  are  very  slight,  the  saliva  being  acid  from  the 
acid-sodium  salts,  the  mucus  which  goes  to  make  films  being  held  in  solution;  it  is 
interesting  to  note  that  these  are  the  very  types  where  the  cement  line  fails  most 
rapidly,  so  that  it  would  appear  that  the  film  is  protective  of  the  cement  line  unless, 
as  he  says,  acid  be  formed  in  and  under  it  or  "at  the  very  point  where  enamel  is 


Fig.  XXIV 

Fig.  XXIV.     From  J.  Leon  Williams'  "A  Contribution  to  the  Study  of  Pathology  of  Fnamel," 
Cosmos,  1897,  showing  film  present  on  all  teeth. 

attacked"  under  the  cover  of  the  film,  and  this  again  is  most  con\incing,  for  it  is  the 
other  and  opposite  type  of  mouth  acidity,  the  Hypo-acid,  where  the  carbohydrate 
percentage  in  the  mucus  is  so  high  as  to  produce  acid  fermentation  in  the  film. 

Black  disagrees  sharply  with  Williams  in  associating  all  films  with  caries,  saying: 
"It  seemed  that  he  included  all  manner  of  material  that  contained  micro-organisms 
(practically  any  material  clinging  to  the  teeth  contains  them),  going  wide  of  the  line 
of  those  forms  known  to  produce  caries.  He  seems  also  to  have  included  deposits 
through  which  water  would  run  so  easily  that  they  would  be  no  bar  to  the  washings 
by  saliva;  such  coatings  are  found  plentifully  over  the  surfaces  of  teeth  of  immune 
persons,  and  also  in  others  where  there  is  no  decay  of  enamel.  Careful  study  shows 
that  many  kinds  of  deposits  upon  the  teeth  present  similar  appearances  when  seen 
in  microscopic  section  to  those  produced  by  gelatinous  plaques  and  3'et  seem  to  have 
no  influence  whatever  on  the  localization  of  caries'',"  Fig.  XX III. 

Blacki"  agrees  with  Williams  that  general  mouth  acidity  cannot  produce  caries, 

10.     Black,  G.  V. — Discussion  of  Miller's  Paper:     "A  Study  of  Certain  Questions  Relating  to  the 
Pathology  of  the  Teeth."     Proceedings,  Fourth  International  Dental  Congress,  Vol.  I. 


54  PRACTICAL  MANUAL  OF  DENTAL  CASTING 

and  insists  that  caries  is  due  to  a  special  gelatinoid  plaque,  saying:  "I  want  it 
understood  that  I  mean  a  gelatinous  substance.  I  do  not  mean  accumulations  of 
micro-organisms  loosely  held  together  on  the  surface  of  the  tooth  *  *  *  in- 
spissated mucus  *  *  *  greasy  accumulations  or  any  of  these  things;  I  mean 
a  substance  that  is  gelatinoid  or  gelatin-like  *  *  *  not  soluble  or  meltable  as 
gelatin".  I  have  grown  the  plaque  artificially,  have  seen  it  in  large  numbers,  and  I 
am  sure  that  under  certain  dietetic  conditions  it  is  produced." 

Miller  and  Black  thus  boch  agree  that  films  cover  all  teeth  and  do  not  necessarily 
mean  caries. 

Finally,  Kirk"  condenses  the  whole  matter  thus: 

"The  catchy  formula  that  'clean  teeth  will  not  decay'  is  misleading,  even  if  true 
in  the  ideal  sense  *  *  *  first,  because  it  is  equally  true  that  unclean  teeth  do 
not  necessarily  decay;  and,  second,  it  is  practically  impossible  to  always  have  clean 
teeth  in  the  ideal  sense.  *  *  *  For  the  reason  just  stated,  dental  caries  cannot 
logically  or  scientifically,  any  more  than  from  the  standpoint  of  observed  facts,  be 
classed  as  a  filth  disease.  *  *  *  More  particularly  has  attention  been  called  to 
the  fact  that  fermenting  particles  of  carbohydrate  food  debris  adhering  to  tooth 
surfaces  is  not  in  itself  sufficient  to  account  for  the  phenomena  of  caries  of  the  teeth; 
that  the  mixed  saliva  itself  contains  fermentable  substances  as  it  is  excreted  from  the 
glands,  and  that  this  carbohydrate  product  of  nutrition  dialyzed  from  the  blood 
plasma  is  the  element  found  in  the  saliva  of  caries  susceptibles  which  is  the  normal 
pabulum  of  the  lactic  acid  bacteria  concerned  in  the  first  stages  of  tooth  caries  *  * 
salivary  composition  is  a  resultant  of  nutrition,  and  that  in  its  turn  is  dependent  in 
a  large  degree  upon  food  habit." 

It  is  thus  shown  that  the  chemical  composition  of  the  saliva  and  the  growth 
and  chemical  composition  of  the  films  forming  upon  enamel  surfaces  is  dependent 
upon  the  nutritional  state,  and  this  is  most  impressive  when  we  find  that  the  cement 
line  is  damaged  most  rapidly  and  without  caries  in  the  erosion  mouths  of  the  Hyper- 
acid diathesis,  where  there  is  coincident  acidity  of  saliva  and  solution  of  mucus  with 
few  films;  that  it  suffers  almost  as  much,  attended  this  time  by  rapid  caries,  in  the 
mouths  of  the  Hypo-acid  diathesis,  where  there  is  coincident  acidity  of  saliva  and 
excessive  mucus,  acid  from  its  fermenting,  carbo-hydrate  content  forming  a  thick 
"felt"  of  acid  films.  Fig.  XXIV,  and  finally,  it  is  damaged  least  of  all  in  the  normal 
mouths,  where  the  saliva  and  mucus  are  alkaline  and  films  grow  freely,  but  are 
alkaline  from  putrefaction  of  the  normal  nitrogenous  content.  Fig.  XXIII. 

It  would  thus  appear  that  there  is  also  something  mechanically  protective 
against  mouth  fluids  in  normal  mucus  and  its  films  when  the  film  is  not  acid-produc- 
ing in  itself,  Williams  saying,  "This  mass  of  fungi  is  so  dense  and  adhesive  as  to  make 
it  highly  improbable  that  enamel  is  affected  by  any  acid  other  than  that  which  is 
being  excreted  by  bacteria  at  the  very  point  where  enamel  is  attacked,"  and  Black 
insists  on  the  tough  adhesive  agglutination  to  enamel  surfaces  of  the  gelatinoid 
plaque,  maintaining  that  no  dilutions  can  occur  from  the  fluid  of  the  saliva  under' 
these  growths.  Fig.  XXIV. 

So  we  take  it  as  proven  that  the  only  danger  to  the  cement  joint  would  be  the 
excessive  acidity  of  the  contained  film ;  the  total  absence  or  the  continued  displacement 
of  the  film,  or  so  slight  a  growth  as  to  allow  entrance  of  a  generally  acid  saliva,  and 

9.     Black,  G.  V. — Discussion,  Report  of  the  Committee  on  Scientific  Research,  Dental  Society,  State 
of  New  York  — Denial  Cosmos,  1906. 
11.     Kirk,  E.  C. — Editorial:     Prophyla.xis. — Denial  Cosmos,  Feb.,  1911. 


THE  CEMENT  LINE  IN  INLA  YS  55 

while  Black  says,  "The  acidity  of  the  general  saliva  does  not  become  sufficient  to 
cause  caries.  Those  immune  to  caries  have  saliva  fully  as  acid  as  those  intensely 
susceptible,"^  it  must  be  recalled  from  the  work  of  Hinkins  and  Head  that  cement  is 
much  more  vulnerable  to  mouth  acids  than  is  enamel. 

Relative  to  the  dangers  of  oral  mucus,  you  are  referred  to  the  workof  Lohman, 
who  claims  that  mucus  is  the  direct  acting  cause  of  all  carious  processes,  and  to 
Kirk'  ''and  Miller's'  ''discussion  of  this  theory,  with  which  they  do  not  at  all  agree 
only  in  so  far  as  has  been  previously  quoted;  the  writer*"  believes  that  "  If  mucus  were 
destructive  rather  than  preservative  of  enamel  continuity,  teeth  in  our  race  would 
cease  to  exist,  so  thoroughly  are  they  encased  by  it."  Of  course,  this  is  the  normal 
mouth  mucus,  the  same  no  doubt  to  which  Head'  refers  when  he  says  of  the  cement 
line,  "The  mucus  gets  into  the  fine  line  and  acts  as  a  capillary  plug,  preventing  the 
constant  interchange  of  solvent  fluids." 

The  presence  of  a  protective  film  in  inlay  joints  under  certain  conditions  now  under- 
stood cannot  be  Questioned;  as  to  just  hotv  the  film  protects  the  contained  cement,  that 
needs  further  investigation. 

It  is  the  writer's  idea  that  films  fill  the  crevice  left  by  the  earliest  washout  of  the 
superficial  cement  almost  as  soon  as  the  inlay  is  set,  and,  as  soon  as  they  are  retained, 
alkaline  putrefaction  begins  and  the  contained  film  becomes  alkaline  and  discolors; 
if  the  film  is  of  sufficient  density  and  agglutination,  the  cement  line  is  protected  until 
the  film  is  displaced,  Fig.  XIII.  If  the  mouth  be  of  the  Hypo-acid  diathesis,  with 
its  high  percentage  of  carbohydrate  in  the  film,  acid  fermentation  occurs  in  the 
contained  film,  the  lactic  acid  attacks  the  cement,  which  is  alkaline,  to  solution 
until  the  acid  is  neutralized  and  the  film  becomes  alkaline  and  protective;  if  this  is 
displaced,  as  is  often  the  case,  the  process  repeats  itself  until  the  "wash-out"  becomes 
so  deep  and  the  renewed  film  so  acid,  that  it  cannot  be  neutralized  by  the  dissolving 
cement  under  it,  when  decalcification  of  the  cavo-surface  enamel  occurs  and  caries 
begins. 

It  might  be  argued  that  the  ordinary  decalcification  of  enamel  would  also  neutral- 
ize the  acidity  of  the  attacking  film,  and  that  caries  should  then  cease,  and  it  does,  but 
only  to  begin  again,  as  all  know  who  have  attempted  carious  cultures;  for  when  the 
percentage  of  acidity  of  the  culture  media  gets  too  high  it  must  be  neutralized  b\-  a 
slight  addition  of  alkalines;  it  is  just  this  intermittent  alkalinity  which  makes  caries 
of  enamel  possible,  but  the  amount  of  alkalinity  produced  by  slow  caries  of  enamel 
is  small  when  compared  with  the  acid  neutralization  possible  in  rapid  cement  solution. 

There  are  as  many  stages  to  this  process  of  maintaining  the  alkalinity  of  the  con- 
tained film  as  there  are  gradations  from  the  normal,  from  the  simple  neutralization 
of  a  slightly  acid  film,  and  its  agglutination  and  retention  to  the  dangerous  combina- 
tion in  the  -vulnerable  mechanical  areas  named,  where  the  cement  and  contained 
films  are  pumped  out  by  bite  stress,  only  to  be  replaced  by  other  deeper  acid  films, 
and  so  on  to  complete  joint  destruction. 

This  is  the  usual  history  of  the  destruction  of  the  ordinary  cement  filling:  in  the 
occlusal  areas  it  is  washed  and  the  film  rapidly  removed;  in  the  gingival  areas  the  film 
is  retained,  but  in  such  mass  and  constantly  changing  that  it  is  neutralized  by  the 

15.  Lohman.  A. — A  Ngw  Fact  About  Dental  Caries. — Archiv..  June.  1904. 

16.  Kirk,  E.  C. — Editorial:     "Mucin  as  a  Factor  in  Dental  Caries." — Denial  Cosmos,  1904. 
18.     Miller,  W.  D. — New  Theories  Concerning  Decay  of  Teeth. — Denial  Cosmos.  1905. 

6.     Grieves.  C.  J. — Report  of  Work  on  Base  vs.  Noble  Metals  in  Orthodontia. — Items  of  hilerest, 
Feb..  1910. 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 

alkalinity  of  the  dissolving  cement  only  to  be  replaced  by  a  larger  film  of  higher 
acidity,  and  there  is  no  retention  of  film.  From  a  protective  standpoint,  agglutina- 
tion of  the  film  and  its  retention  are  the  most  necessary  things  in  inlay  work,  as  shown 
by  all  these  investigations,  and,  clinically,  the  rule  holds  good,  viz.,  the  finer  the 
joint,  the  less  the  film;  if  it  be  acid,  the  less  to  neutralize,  and  the  better  the  retention 
of  it. 

It  is  now  easy  to  understand  how  the  finest  contact  operations  may  fail  Avhile 
the  ordinary  cement-joint  may  stand  in  the  same  embrasure,  for  if  the  contact  opera- 
tion falls  short  at  any  point  of  absolute  contact,  capillarity  acts,  fluids  enter,  and  the 
crevice  fills  with  acid  film.  Fig.  XXV,  which  so  slowly  attacks  the  cavo-surface  enamel 
that  the  contained  film,  instead  of  being  neutralized,  receives  just  the  percentage 
of  alkalinity  sufficient  to  maintain  caries;  in  the  cemented  joint,  as  has  been  shown, 
the  acidity  of  the  film  acts  quickly  on  the  more  susceptible  substance  present,  the 
cement,  and  the  film  is  made  alkaline,  Fig.  X,  XI,  XII,  XIII. 

With  all  these  facts  in  mind  the  operator  may  approach  a  mouth  for  inlay  work 
with  some  assurance  of  his  knowledge,  first  of  the  diathesis,  and  by  that  judge  how 


Fig.  XXV 

Fig.  XXV.  A — Linguo-incisal  view  of  one  of  the  best  malleted  gold  contours  the  writer  has  ever 
examined,  lioned  to  the  dentine;  "a"  dentine,  "b"  gold  filhng.  Note  the  stain  from  leakage  at  "c" 
in  the  vulnerable  incisal  angle;  time  in  the  mouth,  eight  years. 

B — A  cross  section  cut  through  a  bicuspid  from  bucco-gingival  to  linguo-occlusal  of  the  best  amal- 
gam filling  yet  seen  by  the  writer;  "a"  dentine,  "b"  amalgam  filling,  "d"  edges  failing  from  bite 
stress,  "c"  recurrent  caries;  time  in  the  mouth,  nine  years. 

Q — View  of  the  mesio-buccal  angle  bicuspid  of  a  well-appearing  silicate,  six  months  in  the  mouth; 
"a"  enamel,  "b"  silicate  filling.     Note  the  open  joint  at  "c." 

his  work  may  stand,  of  the  vulnerable  areas  in  cavity  preparation,  and  as  to  which 
type  of  joint  he  may  use,  porcelain  and  butt-joints  for  appearance  when  sheltered, 
or  a  shelter  can  be  made  by  inssetting  in  lap-joint  gold  inlays,  which  are  always 
preferable  for  accuracy  and  durability. 

Finally,  the  future  of  the  method  of  inlaying  fillings  in  teeth  will  be  dark  indeed, 
and  this,  the  greatest  boon  of  our  times  to  both  patient  and  operator,  will  be  cast 
aside  as  "weighed  and  found  wanting,"  if  we,  as  a  profession,  are  satisfied  with 
present  results.  As  seen  in  the  light  of  these  investigations  the  field  is  only  just 
invaded.  It  will  not  do  to  accept  the  present  cavo-surface  union  of  porcelain  inlays 
with  the  smug  statement,  "That  joints  will  wash  out  any  way,  so  what's  the  use?" 
any  more  than  it  will  serve  to  be  comfortably  pleased  with  our  lap-joints  in  gold 
inlays.  We  are  convinced  that  both  butt  and  lap-joints  by  suitable  technique  must 
be  made  the  equal  of  those  found  in  the  finest  foil  operations.  It  is  going  to  demand 
some  of  the  finest  science,  art  and  skill  that  our  profession  has  ever  displayed  to  do 


THE  CEMENT  LINE  IN  I  NLA  YS  57 

this  thing,  and  we  feel  assured  that  in  time  the  skill  will  be  displayed,  the  science 

applied,  the  art  demanded  put  to  practice,  for  never  3^et  have  we,  as  a  profession, 

failed,  when  convinced  of  the  need,  in  the  accomplishment  ofttimes  of  the  seemingly 

impossible. 

DISCUSSION 

W.  T.  Reeves,  Chicago,  111.:  I  am  thoroughly  in  accord  with  all  of  the  subject  matter  as  Dr. 
Grieves  has  presented  it.  I  believe  that  you  will  find  that  when  the  paper  appears  in  print  and  you  have 
had  a  chance  to  study  it  and  to  go  over  it  not  only  once  but  several  times,  you  will  get  great  benefit 
from  it. 

Now,  I  think  that  Dr.  Grieves  has  summed  up  his  conclusions  that  the  filling  that  depends  upon  a 
cemented  joint  has  proven  far  superior  to  the  contact  filling,  or  the  gold  or  amalgam  filling  as  it  usually 
has  been  put  in.  As  he  said  in  that  paper,  the  amalgam  filling  that  has  a  cement  lining  is  far  superior 
to  the  filling  that  has  no  cement  under  it.  His  conclusion  came  to  the  point  that  the  minimum  joint, 
and  the  minimum  amount  of  cement  under  the  filling,  gives  the  highest  degree  of  result.  He  also 
spoke  about  inlay  operators  differing,  as  to  those  who  have  a  fit  of  the  cavity  throughout  and  those 
who  have  only  a  fit  of  the  cavity  at  the  margin  and  depend  upon  a  bulk  of  cement  in  the  interior  of  the 
cavity.  He  divides  the  subject  as  between  butt  joints  and  lap  joints,  and  shows  how  it  is  possible  to 
obtain  lap  joints  with  a  gold  inlay.  It  is  true  it  is  only  possible  to  obtain  lap  joints  with  a  gold  inlay 
in  the  way  that  he  has  outlined,  through  cavity  preparation.  It  is  also  true  that  in  all  butt  joint 
operations,  you  are  limited  as  to  your  ability  to  set  that  inlay  to  its  place. 

We  will  take  the  cavity  preparation  that  you  have  been  making  for  gold  inlays — and  I  take  it 
there  are  a  greater  percentage  of  the  audience  who  use  gold  inlays  than  who  use  porcelain  inlays.  I 
believe  that  in  all  that  I  have  seen  and  heard  on  the  subject,  that  you  are  following  in  your  cavity 
preparation  a  cavity  form  very  similar  to  that  advocated  for  gold  foil  fillings,  that  credited  to  Dr.  Con- 
zant,  in  which  Dr.  Grieves  says  is  his  ideal  cavity  preparation.  I  differ  very  decidedly  from  that  cavity 
preparation.  You  have  followed  that  cavity  preparation  through  your  teachings  and  training  in  the 
association  of  gold  foil  fillings  in  which  you  have  had  to  have  a  retentive  form  of  cavity  and  interlocking 
form  of  filling,  and  you  are  following  out  that  belief  that  it  is  mechanics  that  also  governs  to  a  large 
e.xtent  the  retention  of  inlays  in  your  cavity.  I  am  still  preaching  that  it  is  not  mechanics  in  any  sense 
whatever.  You  may  have  a  mechanical  form  of  cavity  that  will  hold  that  filling  in,  before  any  medium 
is  used  to  hold  it  in  the  cavity.  It  will  not  dislodge,  but  after  the  filling  has  been  set  mechanics  does 
not  enter  into  play  until  the  cement  joint  is  broken — the  cement  joint  breaks  all  over  the  cavity  in  one 
instant.  Consequently  your  mechanical  fit  will  not  enter  into  play.  The  greater  area  of  surface  you 
have,  the  greater  degree  of  adaptation  to  that  surface,  and  consequently  the  greater  amount  of  retention, 
the  greater  pounds' pressure  resistance  there  will  be  to  its  dislodgment.  I  do  not  wish  to  carry  the 
discussion  away  from  the  paper  whatever,  and  I  think  the  deductions  of  the  paper  bring  us  to  the 
point  that  the  minimum  amount  of  crevice,  or  joint,  gives  us  the  greatest  amount  of  security.  That 
is,  there  can  be  less  washout  through  mechanical  force,  if  the  cement  does  not  wash  out,  and  I  believe 
it  is  a  well  established  clinical  fact  that  the  cement  in  a  well  fitted  inlay  will  not  wash  out  but  half  the 
diameter  of  the  crevice.  Now,  our  object  should  be  to  obtain  a  fit  of  cavity  throughout,  as  well  as  at  the 
margins,  as  great  as  you  have  obtained  in  your  cast  gold  inlays. 

The  next  point  is,  have  no  butt  joints  at  any  portion  of  the  cavity.  You  well  know  that  we  cannot 
take  a  flat  surface  of  cavity  and  force  the  cement  out  to  allow  you  to  close  that  to  the  greatest  degree 
possible.  If  your  cavity  preparation  will  take  more  of  what  might  be  termed  a  wedge  shape  you  then 
may  be  able  to  set  it  with  a  minimum  amount  of  cement.  If  I  had  a  diagram  (I  wish  I  had  known  just 
what  the  illustrations  had  been,  I  would  have  made  a  diagram  to  illustrate  what  I  want  to  give  you  as 
my  form  of  a  lap  joint  in  a  porcelain  inlay,  because  I  use  that  almost  exclusively).  I  ha\e  a  small 
model  here  that  I  use  in  teaching.  It  has  been  in  use  for  a  dozen  of  years,  but  I  am  afraid  it  is  too 
small  for  you  to  see.  If  the  filling  enters  on  the  wedge  principle,  in  doing  so  >ou  are  able  to  force  your 
inlay  into  the  cavity  and  secure  the  minimum  of  joint.  You  will  see  that  there  is  at  no  place  anything 
of  the  nature  of  a  butt  joint. 

I  have  seen  a  number  of  times  in  print  and  heard  a  number  of  times,  and  Dr  Grieves  has  spoken 
to  you  tonight  in  regard  to  porcelain  inlay  men  speaking  of  the  washout  of  the  cement  in  their  joint  as 
advantageous  to  their  filling,  and  that  it  helps  in  the  making  of  the  porcelain  to  match  the  tooth.  I  do 
not  know  as  I  can  in  any  way  illustrate  just  what  I  would  like  to  show  you.  If  there  is  a  portion  that 
would  be  a  butt  joint,  and  if  filled  with  cement,  the  shadow  would  be  cast  directly  into  the  inlay,  but 
if  you  prepared  that  so  there  is  no  butt  joint,  you  will  see  that  your  shadow  is  cast  downwards  and 
backwards,  so  that  the  shadow  of  the  cement  passes  out  through  the  inlay  below  the  median  line  and  it 
does  not  cast  a  shadow  into  your  porcelain. 

Another  point  is  the  conditions  of  the  mouth  that  Dr.  Grieves  speaks  of  in  connection  with  erosion 


58  PRACTICAL  MANUAL  OF  DENTAL  CASTING 

those  conditions  where  porcelains  look  well  but  are  soon  dislodged  because  of  the  loosening  of  the 
cement.  That  is  very  true,  but  in  the  same  mouths  gold  foil  fillings  fail  as  quickly.  I  have  found  that 
in  that  class  of  cases,  it  I  extend  the  cavity  considerably  beyond  the  area  that  has  been  affected  by  the 
erosion,  then  the  acid  that  is  precipitated  will  be  dissipated  by  the  saliva  before  it  reaches  the  margin, 
and  those  cases  that  formerly  were  soon  dislodged  I  have  had  no  difficulty  about  their  remaining  in 
the  cavity. 

■  As  I  said  at  the  start,  I  think  the  great  value  of  Dr.  Grieves'  paper  will  come  to  you  when  you  are 
able  to  read  it.  I  hope  it  will  convince  you  that  the  inlay  principle  of  filling  teeth  really  is  the  correct 
principle.  In  a  great  majority  of  cases  it  will  preserve  more  teeth  than  any  other  method  that  we 
have  used.     The  time  is  late,  and  I  thank  you  very  much  for  your  attention. 

S.  F.  GiLMORE,  Indianapolis:  The  wisest  man  that  ever  lived  said:  "As  iron  sharpeneth  iron,  so 
doth  the  countenance  of  man  his  friend."  And  I  want  to  leave  it  to  you  if  your  minds  have  not  been 
sharpened  by  the  countenance  of  Dr.  Grieves,  and  by  his  paper,  what  he  has  said  and  what  he  has 
illustrated.  As  I  listened  to  his  paper  the  quoted  proverb  came  into  my  mind — "As  iron  sharpeneth 
iron,  so  doth  the  countenance  of  man  his  friend." 

1  have  longed  for  some  light  on  this  very  subject  that  has  been  so  wel'  presented,  and  now  1  can  say 
that  I  have  the  light  that  I  sought.  There  is  one  question  that  forces  itself  upon  the  mind  of  every 
operator  as  he  is  giving  the  final  and  finishing  touches  to  a  filling  of  whatever  character  it  may  be, 
perhaps  a  beautiful  gold  inlay.  It  is  a  question  that  he  asks  himself,  and  the  query  is,  "How  long  will 
this  filling  preserve  this  tooth;  how  long  will  it  last?"  and  echo  answers,  "How  long?"  He  says  he 
thinks  it  will  last  for  years,  but  as  a  matter  of  fact  he  doesn't  know.  The  wish  may  be  father  to  the 
thought. 

I  feel  especially  honored  at  being  appointed  as  one  to  open  the  discussion  of  this  paper.  To  discuss 
a  paper  from  the  pen  of  Dr.  Grieves  of  Baltimore  is  a  thing  that  I  am  utterly  incapable  of  doing,  but 
then,  there  is  nothing  to  discuss;  it  is  all  to  commend.  The  man  who  discusses  usually  feels  called  upon 
to  differ  with  the  essayist  in  some  particular.  In  this  case,  to  controvert  is  out  of  the  question.  It 
would  be  like  essaying  to  differ  with  a  man  who  said  that  two  and  two  are  four;  there  is  no  ground  for 
argument.  You  know  there  are  so  many  men  who  make  deductions,  that  have  their  origin  in  fancy; 
they  fancy  they  will  exploit  that  fancy  and  fancy  that  you  will  believe  it.  And  while  I  concede  the  fact 
that  Dr.  Grieves'  deductions  do  not  have  their  origin  in  fancy,  but  rather  are  the  result  of  careful, 
intelligent,  painstaking,  scientific  research  and  observation,  yet  I  must  have  a  word  with  Dr.  Grieves 
on  one  particular  point:  on  the  matter  of  giving  preference  to  a  cemented  joint  in  what  is  termed  the 
vulnerable  chemical  area,  over  one  of  perfect  contact  of  metal  to  tooth. 

Now,  this  perfect  contact  of  metal  to  tooth  may  be  had  by  a  properly  manipulated  high-grade 
amalgam,  thoroughly  burnished  and  perfectly  adapted  to  the  cervical  wall  of  a  cavity  that  is  so  situated 
as  to  be  practically  inaccessible  to  direct  vision,  or  after  a  filling  is  inserted,  inaccessible  to  even  reflected 
vision.  The  class  of  cavities  that  I  refer  to  are  those  deep  ones  on  the  disto-proximal  surfaces  of  molars, 
superior  or  inferior;  those  dark  corners  where  you  cannot  see  what  you  are  doing,  or  what  you  have  done 
after  you  have  done  it.  The  insertion  of  an  inlay  in  such  a  locality  is  always  accompanied  by  a  feeling 
of  doubt  on  the  part  of  the  operator  as  to  whether  or  not  he  has  secured  good  contact  at  the  cervical 
wall,  as  to  whether  or  not  there  is  proper  alignment  between  metal  and  tooth  surface.  If  his  exploring 
point  conveys  the  information  that  the  gold  overhangs,  he  finds  it  impossible  to  burnish  to  any  ad- 
vantage through  the  embrasures.  His  patient  will  not  submit  to  it;  all  efforts  to  do  so  result  in  ir- 
reparable damage  to  the  soft  and  sensitive  tissue.  If  he  has  accidentally  produced  an  inlay  entirely 
free  from  overhang,  if  he  has  a  perfect  alignment  between  metal  and  tooth,  what  assurance  has  he  that 
the  shrinkage  of  his  casting  has  not  resulted  in  too  fat  a  joint  to  be  dependable,  especially  in  a  butt 
joint? 

As  our  essayist  says,  "A  greater  number  of  failures  may  be  noted  at  this  point,  the  vulnerable 
chemical  area,  than  at  any  other,  for  the  evident  reason  that  the  correct  setting  and  finishing  of  the  lap 
under  the  gingivus,  without  damage  thereto,  or  overflange,  causing  retention,  is  one  of  the  most  difficult 
procedures  in  operative  dentistry,  and  needs  much  bellermenl." 

In  my  experience  with  inlays  of  the  malnx  type,  I  have  discovered  that  the  weak  point  is  the 
cervical  wall,  principally  in  all  cavities  of  the  class  referred  to;  that  perfect  adaptation  and  surface 
alignment  is  out  of  the  question;  and  that  without  these  important  factors,  recurrent  caries  at  the  gin- 
gival margin  is  the  result  in  most  cases.  As  the  result  of  my  experience  along  this  line,  I  have  adopted 
and  practice  what  I  have  proven  in  my  own  experience,  at  least,  to  be  a  satisfactory  solution  of  this 
problem:  All  cavities  having  a  gingival  wall  or  border  that  are  not  accessible  to  reflected  vision,  or 
satisfactory  instrumentation,  after  the  filling  is  seated,  should,  as  a  part  of  their  preparation  for  an 
inlay,  have  at  least  a  layer  of  amalgam,  one  or  more  millimeters  in  thickness,  vigorously  and  thoroughly 
burnished  to  contact  with  said  wal).  A  careful  adaptation  of  the  matrix  will  make  this  method  an  easy 
matter,  because  the  modern  matrix  properly  adapted  automatically  produces  contact  and  alignment. 
All  that  is  necessary  is  for  you  to  apply  the  force. 


THE  CEMENT  LINE  IN  I  NLA  YS  59 

This  method  carries  with  it  the  sustaining  argument  that  the  element  of  guess  work  is  largely 
eliminated,  so  far  as  adaptation  is  concerned.  The  field  of  operation  is  brought  up  to  a  point  where 
the  operator  can  see  what  he  is  doing.  What  a  comfort  it  would  be  if  we  could  see  exactly  what  we  are 
doing  in  a  large  number  of  the  operations  we  perform  in  the  human  mouth.  What  a  comfort  it  would 
be  if  the  element  of  guess  work  could  be  eliminated,  when  we  are  preparing  for  filling  a  canal  that  is 
filled  with  deleterious  matter.  If  we  could  only  see  when  we  have  the  last  bit  of  septic  matter  out  of 
that  canal,  and  when  we  have  properly  sterilized  it  for  its  filling;  if  we  could  see  our  gutta  percha  point 
carried  just  to  the  right  spot.     Speaking  about  comfort,  I  am  tempted  to  tell  a  story: 

An  Irishman  and  a  Dutchman  were  working  side  by  side  on  a  public  highway,  and  as  they  worked 
they  talked.  Among  the  various  things  they  talked  about  was  the  subject  of  what  was  the  most 
delicious  article  of  diet.  The  Irishman  thought  nothing  could  excel  the  Irish  potato.  The  German  said 
there  was  nothing  that  could  equal  Limburger  cheese.  The  Irishman  had  never  heard  of  Limburger 
cheese  and  it  was  new  to  him.  The  German  said  to  him,  "I  will  convince  you;  I  will  have  my  grocer 
send  you  up  ten  pounds  of  Limburger  cheese  and  I  want  you  to  feel  that  you  are  putting  your  feet  under 
a  table  that  is  groaning  with  the  best  thing  it  is  the  privilege  of  man  to  consume."  When  the  Irishman 
went  home  that  evening  he  saw  Martha  standing  as  he  approached  the  house,  with  a  cloud  on  her  face, 
and  she  said  to  him,  "Mike,  you  better  not  come  in;  well — maybe  you  better  come  in."  Mike  said, 
"Did  a  man  bring  something  here?"  and  Martha  answered,  "Yes;  the  grocer  brought  something  up 
and  it  is  spoiled,  whatever  it  is,  and  the  odor  of  it  in  the  house  is  awful.  I  wish  you  would  come  in." 
Mike  agreed  with  his  wife  that  whatever  was  sent  was  a  mistake  and  was  badly  spoiled.  His  Irish 
neighbor  came  in  for  an  evening  call,  and  he  sat  there  and  talked  about  one  thing  and  another.  Finally 
his  curiosity  got  the  better  of  him  and  he  said,  "  Mike,  have  you  had  a  death  in  the  family?"  Mike  was 
loath  to  acknowledge  the  cause  of  the  trouble,  so  he  thought  the  best  way  out  of  it  was  to  say  yes.  His 
friend  said,  "Mike,  was  it  one  of  the  family?"  and  Mike  said  "Yes."  "I  hope  it  wasn't  one  of  the 
children,"  and  Mike  said,  "No,  it  was  my  mother-in-law."  His  friend  said,  "Well.  Mike,  it  is  an  awful 
thing  to  lose  a  mother-in-law,  but  you  have  one  thing  to  comfort  you.  When  you  come  to  bur>-  her  you 
will  not  be  afraid  she  is  in  a  trance — she  is  sure  enough  dead." 

When  a  man  puts  in  a  gold  inlay  he  satisfies  himself  in  every  way  that  it  is  a  beautiful  inlay,  and 
his  patient  compliments  him.  In  the  course  of  time  his  patient  comes  back  and  takes  his  seat  in  the 
operating  chair,  and  says:  "You  know  that  beautiful  inlay  you  put  in,"  and  you  pass  your  instrument 
in  there  and  it  goes  into  a  hole,  and  you  find  debris  and  one  thing  and  another.  You  are  satisfied  at 
once  that  whatever  was  in  there  is  not  in  a  trance,  anyway. 

I  submit  that  the  experience  of  every  operator  present  and  the  history  of  every  amalgam  filling 
that  has  been  carefully  and  conscientiously  planted  against  the  cervical  wall  of  a  cavity,  would,  if  such 
history  were  available,  bear  me  out  in  the  statement  that  a  smaller  percentage  of  recurring  caries  may 
be  found  in  what  our  esteemed  essayist  has  designated  as  "the  vulnerable  chemical  area,"  where 
amalgam  has  been  employed,  than  that  of  any  other  filling  material.  If  you  use  this  method  you 
need  not  give  yourself  much  concern  as  to  whether  or  not  the  oral  secretions  remain  normal  or  change 
to  Hyperacid  or  Hypoacid  conditions.  One  of  the  old  dependable  wheel  horses  of  the  dental  profession 
can  still,  as  in  the  past,  be  depended  upon. 

Now,  will  you  tell  me  of  any  good  and  valid  reason  why  you  should  not  employ  a  thin  film  of 
quick-setting  amalgam  under  an  inlay  in  the  territorj'  referred  to,  and  then  comfort  yourself  with  the 
thought  that  your  beautiful  inlay,  with  its  perfect  lap  joints,  lingually,  buccally  and  occlusally,  will 
stand  as  a  monument  to  your  skill  and  not  eventually  topple  over  because  it  was  undermined? 

Alexander  Jameson.  Indianapolis,  Ind.:  When  I  received  a  copy  of  this  paper  by  Dr.  Grieves  I 
had  the  feeling  that  the  gentleman  who  selected  me  to  discuss  the  same  did  not  show  as  fine  perception 
or  as  good  judgment  as  he  should  have  shown.  I  think  that  it  requires  to  discuss  this  paper  somewhat 
of  a  mechanic,  a  good  deal  of  an  artist,  a  great  deal  of  a  bacteriologist,  and  a  man  who  is  more  or  less 
a  past  master  in  several  of  the  arts  that  the  average  dentist  has  not  time  to  look  into.  In  other  words, 
it  presupposes  more  ability  than  I  have. 

However,  there  are  some  points  that  I  particularly  want  information  on.  It  is  no  discussion  of  a 
paper  to  get  up  and  say  that  it  is  well  read  and  well  presented.  We  all  know  that,  and  this  paper  shows 
a  wonderful  amount  of  investigation  and  research.  I  want  to  cut  my  remarks  short  and  get  down  to 
the  gist  of  the  matter  and  find  out,  for  instance,  where  this  fits. 

There  is  a  lesson  to  be  learned  in  everything  of  this  kind,  from  every  effort  that  is  an  honest  effort, 
and  this  one  undoubtedly  is,  and  we  want  to  draw  our  conclusions  where  this  fits  into  our  everj'day 
practice  and  life. 

We  are  assured  that  the  lap  joint  inlay  is  fll-en  better  than  we  thought  it  was.  However,  I  want  to 
get  back  of  a  few  things.  I  have  never  had  much  doubt  of  one  thing,  and  I  hope  you  won't  hit  me  with 
a  brick  when  I  say  it.  I  believe  the  average  man  doing  the  average  work  can  do  a  better  piece  of  work 
with  an  inlay  than  he  can  with  a  gold  filling.     That  does  not  prove  anything,  however. 


60  PRACTICAL  MANUAL  OF  DENTAL  CASTING 

Dr.  Grieves  has  shown  by  a  great  many  figures  and  beautiful  illustrations  the  cement  line  under 
these  fillings.  He  has  drawn  a  conclusion  himself  that  the  cemented  filling  is  better  than  the  contact 
filling.  On  the  other  hand,  to  go  back  and  be  scientific  about  it,  he  has  not  given  us  the  history  of  those 
pictures.  I  doubt  whether  there  are  any  of  those  cemented  fillings  that  are  as  old  as  some  of  the  con- 
tact fillings  that  Dr.  Grieves  has  not  had  a  chance  to  see.  As  a  clinical  proposition  I  have  got  to  be 
shown  that  the  right  kind  of  a  contact  filling  isn't  about  right.  If  it  is  not  the  right  kind  it  may  fall 
into  the  hands  of  Dr.  Grieves  and  be  dissected  and  thrown  upon  the  screen.  He  hasn't  told  us  how  old 
they  were,  etc.  I  think  they  both  ought  to  be  put  in  under  the  same  conditions,  live  the  same  life  and 
then  be  subjected  to  the  same  analysis  in  order  to  give  us  something  that  is  scientific.  I  do  not  believe 
the  doctor  said  where  these  fillings  were  from,  how  long  they  had  been  in,  who  put  them  in,  nor  anything 
about  the  conditions.  You  can  take  a  contact  filling  that  has  been  doing  nice  work  in  one  mouth  for 
four  or  five  years,  and  it  will  fail  in  another  mouth.  The  doctor  himself  has  given  us  a  classification 
that  shows  that  any  filling  fails  in  certain  mouths  and  others  do  well.  Now,  those  classifications,  ac- 
cording to  his  own  statement,  might  obtain  in  a  case  of  this  kind.  A  contact  filling  may  have  been  in 
one  of  these  mouths  that  was  not  the  best  place  for  it,  or  a  filling  of  any  kind.  The  cemented  filling 
may  have  been  in  one  where  there  was  all  the  advantage.  Until  we  can  get  data  upon  these  things  that 
are  absolutely  conclusive,  I  would  not  feel  that  his  conclusions  were  absolutely  to  be  relied  upon.  I 
think  he  is  along  the  right  track.     His  work  has  shown  us  some  wonderful  results. 

I  differ  with  the  doctor  in  one  or  two  little  things,  but  I  do  not  know  that  it  makes  any  difference. 
The  doctor  says  that  for  gold  inlays  there  is  nothing  but  pure  gold.  I  think  that  is  a  debatable  proposi- 
tion. The  average  gold  filling  is  harder  than  the  twenty-  or  twenty-two-karat  cast  inlay.  We  have 
seen  many  contact  fillings  that  have  the  characteristic  floor,  and  you  have  a  cemented  filling  that  is 
softer  than  that  is.  The  only  possible  advantage  that  I  know  of  for  gold  filling  would  be  that  it  would 
be  just  a  little  harder  than  the  twenty-  or  twenty-two-karat  gold.  Time  will  tell  and  tell  what  is  the 
best  material. 

Now,  Dr  Grieves'  ideas  and  theories  presuppose  another  thing.  These  classifications  were  made. 
At  the  same  time  my  idea  is  that  those  classifications  more  or  less  come  up  a  good  deal  like  the  old 
question  of  temperament.  We  have  to  be  an  observer  to  tell  anything  about  temperament,  unless  we 
make  quite  a  study  of  it.  We  say  that  so  and  so  had  black  hair,  etc.,  and  a  cenain  temperament 
predominates. 

Now,  to  make  these  classifications  effective  there  should  be  in  every  community  of  dentists  some 
man  or  men  with  a  laboratory  where  we  could  send  our  patients  and  have_  certain  tests  made.  We  know 
in  a  general  way  that  so  and  so  is  so.  We  ought  to  be  able  to  send  our  patients  to  the  laboratory 
and  have  certain  tests  made  to  classify  them.  After  all,  it  comes  down  to  the  proposition,  if  he  belongs 
to  this  particular  class  where  the  lap  joint  fillings  will  preserve  his  teeth,  why  not  make  them  all  lap 
joint?  Why  not  be  hunting  for  the  worst  kind  of  a  case  and  in  doing  that  make  every  filling  the  very 
best  we  can? 

In  the  discussion  last  night  there  were  some  amusing  points  brought  out.  Dr.  Gilmore  makes  a 
statement  that  amalgam  as  a  base  was  the  only  thing  for  a  gold  inlay.  Dr.  Grieves  stated  that  he  al- 
ways puts  an  amalgam  filling  in  with  cement.  Why  not  get  all  these  things  together  and  have  them  all 
right,  have  them  all  there?  I  think  it  would  be  a  great  idea  to  work  all  these  things  in  and  have  a 
proposition  that  would  be  worth  while. 

The  fact  remains  that  I  have  seen  as  a  clinical  proposition  contact  fillings  that  are  in  the  mouth, 
that  have  been  there  as  many  years  as  some  of  us  are  old,  that  are  doing  the  work.  Now,  they  may  be 
in  those  mouths  that  are  more  or  less  immune,  but  some  of  them  are  not.  After  all,  it  comes  down  to 
that  proposition.  The  well  made  contact  filling — well,  you  have  to  show  me  that  it  isn't  all  right. 
Still  I  am  delighted  to  know  that  the  cemented  inlay  is  going  to  have  such  a  good  send-off. 

Now,  the  answer  to  all  this  is  just  one  thing,  and  the  doctor  suggested  the  answer  in  his  paper  last 
night,  and  it  leads  up  to  another  trend  of  circumstances.  Let  us  have  cement  do  the  work.  If  we  go 
to  work  to  get  it  we  will  get  it.  Let  us  get  a  cement  that  is  acid  and  alkaU  proof  and  that  will  do  the 
work.  That  brings  up  the  story  of  the  man  who  said  he  wished  he  had  three  hundred  dollars.  Some- 
one said  to  him,  "If  you  had  three  hundred  dollars  what  would  you  do  with  it?"  He  said,  "Well,  if  I 
had  three  hundred  dollars  I  would  buy  a  sawmill."  His  interrogator  remarked  that  if  he  had  three 
hundred  dollars  he  wouldn't  need  a  sawmill.  If  we  had  a  cement  that  would  do  the  work  why  would 
we  want  a  gold  inlay?  We  have  to  do  the  best  we  can  with  what  we  have.  This  cement  problem, 
after  all,  is  the  answer  to  the  whole  proposition,  in  my  mind. 

Alexander  White,  Indianapolis,  Ind.:  I  would  like  to  bring  out  one  point  that  Dr.  Grieves 
mentioned  last  night,  about  the  use  of  pure  gold  for  all  inlays.  I  believe  he  made  the  statement  that 
he  used  pure  gold  for  all  gold  inlays,  and  I  would  like  to  ask  if  there  are  not  some  indications  for  using 
twenty-two  karat  gold.  I  am  asking  for  information,  as  some  of  our  best  practitioners  use  twentj'-two 
(carat  gold  almost  exclusively,  while  others  claim  they  use  nothing  but  pure  gold.     Which  is  righ^? 


THE  CEMENT  LINE  IN  I  NLA  YS  61 

I  use  pure  gold  almost  exclusively,  but  use  twenty-two  karat  gold  in  some  cases,  as  for  example,  the  use 
of  inlays  for  bridge  abutments. 

Another  point  made  by  Dr.  Grieves'  discussion  was  the  model  a  great  many  of  you  saw.  I  would 
like  to  ask  about  the  gingival  of  that  cavity  preparation  It  is  against  the  principles  taught  by  Dr. 
Black  and  a  great  many  others  to  make  an  upward  slope  of  the  gingival  wall.  They  teach  us  to  make  a 
flat  gingival  base  bevel  the  outer  margin  down,  while  he  has  the  entire  margin  to  slope  upward.  Know- 
ing the  anatomy  of  the  tooth  structure,  I  believe  a  cavity  prepared  in  this  way  will  leave  short  enamel 
rods  to  soon  drop  out.  and  we  will  have  recurrence  of  decay  at  the  gingival  as  shown  by  Dr.  Grieves 
with  the  lantern  slides. 

Closing  by  C.  J.  Grieves,  Baltimore.  Md.:  First  I  want  to  take  up  the  point  just  made  in  Dr. 
Reeves'  discussion  of  my  paper.  I  would  like  very  much  to  have  that  cast,  and  I  want  particularly 
to  express  my  appreciation  of  what  has  been  said  in  regard  to  that  cavity  preparation. 

Dr.  Reeves  said  that  he  made  lap  joints  in  porcelain.  I  think  the  general  opinion  is  that  the  lap 
joint  is  where  the  cavo-surface  enamel  is  lapped  by  the  filling  edge.  That  is  not  the  result  only  of  theory, 
that  is  the  result  of  actual  practice,  as  shown  by  Dr.  Black  and  his  confreres,  and  every  operator  knows 
that  there  must  be  no  short  rods  left.  The  preparation  made  by  Dr.  Reeves  was  just  the  reverse  of  this 
rule.  He  cut  under  his  enamel  wall  and  left  a  lot  of  short  rods  which  overlapped  his  butt  joint.  I 
noticed  in  the  cast  he  presented  that  when  it  came  to  the  incisal  angle,  his  line  was  just  the  same  as  done 
by  any  other  operator,  his  cavo-surface  angle  at  90  degrees,  inasmuch  as  there  was  no  cover  then  to 
the  cavo-surface  cement  and  it  would  be  pumped  out  very  quickly.  Labially  and  lingually  these  short 
enamel  rods  would  soon  chip  oflf;  I  doubt  very  much  if  they  would  stand. 

I  admire  Dr.  Reeves  as  an  operator,  but  I  have  to  say  that  much  about  that  form  of  cavity  prepa- 
ration, inasmuch  as  it  is  just  the  reverse  of  what  is  practiced  by  every  operator  in  all  types  of  filling. 
That  does  not  make  it  wrong;  it  may  be  right  but  I  doubt  it. 

As  to  the  other  point,  the  mechanical  retention,  here  again  I  will  differ  sharply  with  Dr.  Reeves. 
He  said  that  mechanical  retention  amounted  to  little  or  nothing,  that  the  cement  held  the  filling  in  the 
tooth.  The  cement  is  a  retainer,  of  course,  or  we  would  not  use  it,  but  I  have  always  thought  that 
cement  came  into  the  joint  to  close  that  joint,  simply  as  some  adhesive  media,  to  exclude  mouth  juices 
as  between  the  filling  and  the  cavo-surface  enamel.  If  you  are  depending  upon  cement  to  hold  your 
filling,  why  make  any  retention  at  all?  The  fact  of  the  matter  is  that  the  mechanical  retention  I  believe 
time  will  prove,  after  all,  is  the  thing;  the  filling  is  retained  by  mechanical  retention  and  that  in  turn 
retains  the  cement,  and  the  filling  must  have  some  seat  in  the  cavity  that  it  may  find  its  place. 

There  is  a  long  line  which  we  have  not  the  time  to  go  into.  I  think  it  has  been  shown  by  every- 
body who  has  studied  cement  that  all  cements  leak.  I  showed  some  cement  on  the  screen  last  night, 
stained  one-third  the  depth  of  the  walls.  If  they  don't  leak  along  the  joints  their  body  substance  acts 
as  a  filter,  filtering  the  saliva  of  the  germs  in  the  mouth  and  by  this  filtering  process  preventing  decay 
of  enamel.  If  you  will  experiment  you  will  find  the  waterosin  will  go  down  under  the  cavo  wall  in 
cement  fillings.  So  I  am  not  willing  to  depend  entirely  upon  cement  as  a  retainer.  I  want  mechanical 
retention.  I  only  wish  we  could  figure  out  some  way  to  make  a  safe  lap  joint  in  porcelain.  If  you  lap 
your  enamel  the  enamel  chips  off  and  so  does  the  porcelain  when  it  laps. 

The  ne.xt  point,  one  brought  out  by  Dr.  Gilmore,  is  one  upon  which  I  would  like  to  spend  some  time, 
that  about  amalgam.  I  shall  feel  repaid  for  my  trip  here  if  I  have  impressed  you  with  one  thing  of 
value:  I  would  like  to  leave  with  you  the  fact  that  the  cemented-in  filling  of  either  crystal  gold  or 
amalgam  is  the  greatest  thing  in  dental  practice  today.  I  have  been  practicing  this  method  for  eight 
or  ten  years,  the  method  of  working  quick-setting  amalgam  in  slow-setting  cement  in  large  cavities  in 
the  back  of  the  mouth,  and  with  the  oiled  matrix  working  in  and  completing  your  contour  in  amalgam 
you  have  a  filling  which  is  indeed  "cemented  in"  with  a  line  of  cement  much  finer  than  could  be  made 
by  the  most  expert  inlay  operator.  If  you  watch  those  teeth  for  a  year  or  two  you  will  find  there  has 
been  no  discoloration  of  the  surrounding  tooth  structure.  All  that  I  have  said  of  the  cemented-in 
amalgam  I  can  more  than  accent  for  small  fillings  made  of  crystal  golds  in  cement. 

Personally  I  believe  there  is  not  an  amalgam  on  the  market  today  which  does  not  materially  move 
some  time,  or  flow  under  stress,  so  that  I  would  not  trust  Dr.  Gilmore's  proposition  of  laying  amalgam 
bare  at  the  gingival  seat,  neither  do  I  like  the  association  with  gold  in  the  mouth  fluids.  I  firmly  be- 
lieve that  the  reason  amalgam  fillings  save  teeth  is  from  the  fact  that  they  leak  saliva.  One  of  the 
biggest  gynecologists  that  I  know  of  is  placing  a  strip  of  silver  foil  after  large  operations  directly  in 
contact  with  the  exudating  tissue,  the  silver  salts  take  care  of  the  wound,  which  becomes  black  and 
finally  disappears.  So  I  figure  that  the  old  silver  amalgam  filling  leaks  saliva,  and  the  salts  of  the 
saliva  go  down  into  the  dentine  and  make  the  tooth  black,  and  unless  the  crevice  be  a  large  one 'you 
do  not  have  recurring  decay.  Nine-tenths  of  the  average  amalgam  fillings  I  believe  save  teeth  after 
that  fashion. 


62  PRACTICAL  MANUAL  OF  DENTAL  CASTING 

Now,  in  regard  to  Dr.  Jameson's  remarks,  I  did  not  want  him  to  say  what  he  did  about  the  mouth 
classification.  I  do  not  believe  that  it  is  at  all  as  useless  as  the  classification  of  temperament.  I  want 
to  see  every  man  get  to  be  an  expert  in  mouth  diagnosis.  I  believe  it  can  be  done.  That  little  effort 
of  mine  was  the  result  of  the  work  of  other  men  simply  being  compiled,  and  I  believe  we  will  get  to  the 
state  where  we  can  look  into  the  mouth  and  say  what  has  happened  to  that  mouth.  You  are  doing  it 
subconsciously  every  day.  You  are  governed  by  what  you  are  observing  of  the  enamel  surfaces  and 
how  the  work  of  other  men  has  stood.  You  glance  around  that  mouth  and  make  up  your  mind  what 
you  are  going  to  do  in  this  particular  instance  by  what  has  occurred  in  the  past.  Every  man  cannot  be 
an  analyst,  as  the  doctor  says,  of  saliva,  and  I  question  how  much  it  would  help  him  if  he  could,  but  we 
can  have  some  more  definite  idea,  which  I  believe  can  be  made  practically  this  classification. 

Just  as  an  instance — I  have  been  applying  this  method  for  about  two  years  in  my  practice.  T 
would  not  put  a  butt  joint  in  an  erosion  mouth  if  I  could  help  it,  because  I  know  that  the  acid  salts 
would  play  "hob"  with  my  cement.  That  is  a  very  broad  statement.  That  means  your  patients  have 
to  have  lap  joint  or  gold  fillings  in  their  teeth.  We  know  that  porcelain  butt  joints  are  going  to  fail 
in  a  little  while,  and  I  would  trust  a  lap  joint  of  all  things  under  these  conditions,  because  I  think  the 
gold  can  beworked  down  to  such  a  shape  as  will  stand.  Again,  you  instinctively  follow  the  rule  of  the  hypo- 
acid  classification,  where  we  have  everything  fail  in  examining  children.  The  hypoacid  period  is  the 
period  largely  of  childhood.  These  little  children  use  starches,  have  to  have  them.  They  use  sugar; 
it  is  the  carbo-hydrate  food  period.  The  saliva  itself  reflects  their  body  condition,  being  loaded  with 
glycogen.  Under  these  conditions — I  think  you  all  know  a  hypoacid  mouth — (and  I  believe  some 
change  can  be  made  in  the  diet  without  doing  damage  to  the  patient).  You  would  not  put  porcelain 
fillings  in  the  mouth  of  such  a  child  of  the  hypoacid  mouth  variety.  I  believe  that  these  classifications 
have   a   practical    value   every   day. 

If  5'ou  keep  those  three  figures  in  your  mind  and  look  through  the  mouth  you  will  find  that  you  are 
applying  that  more  or  less  and  get  more  skilful  in  it  as  time  goes  along. 

In  regard  to  the  contact  operation,  I  approach  this  subject  with  considerable  temerity.  Before 
I  studied  the  cement  line  I  spent  a  good  deal  of  time  looking  at  every  filling  I  could.  My  method  was 
to  slip  a  rubber  dam  over  every  filling  and  put  formaldehyde  on  the  surface  to  harden  the  films,  then 
stain  these  teeth  after  extracting  and  split  them  open  that  I  might  get  caval  conditions  as  they  actually 
were. 

I  made  a  statement  in  a  former  paper,  of  which  some  of  you  have  copies,  that  personally  I  believe 
that  there  has  never  been  a  contact  operation  made  but  what  leaked  saliva  at  some  point.  In  other 
words,  that  saliva  flows  through  the  joints  and  under  all  fillings.  That  your  contact  operation  suc- 
ceeds, regardless  of  the  fact  that  it  leaks  saliva,  we  all  know,  because  we  have  all  taken  out  hundreds 
of  gold  fillings  that  have  been  leaking,  and  you  have  seen  them  in  scores  the  best  of  contact  operations. 
That  these  fillings  did  not  fail  is  due  undoubtedly,  I  believe,  first  to  the  mouth  conditions.  They  may 
have  been  immune  mouths.  But  principally  I  believe  that  the  protective  film  I  described  has  blocked 
those  joints,  as  we  know  it  does  block  the  cement  joint,  preventing  the  ingress  of  bacteria,  or  isolating 
the  culture  from  its  habitat.  This  is  what  you  find  in  a  leaking  contact  operation  which  has  leaked 
and  yet  is  not  carious. 

I  also  maintain  that  the  well  made  inlay  joint  does  not  leak  except  possibly  a  little,  the  cement 
acting  as  a  filter,  which  was  clearly  shown  by  the  stainfng  in  the  caval  cement  in  my  slides. 

I  tack  my  faith  to  pure  gold,  while  I  recognize  the  truth  of  what  Dr.  Gilmore  has  said.  For  the 
same  reason  that  the  contact  operator  uses  his  pure  gold,  I  claim  that  I  can  make  a  better  joint.  What 
you  are  after  is  the  cavo-surface  contact  between  your  gold  lap  and  enamel,  the  lap  can  always  be 
better  burnished  down.  I  think  the  proof  of  this  is  in  the  burnished  inlay  that  we  used  to  make  of  pure 
gold  matrix  and  solders.  I  made  very  few  joints  which  were  as  good  by  the  old  burnishing  method  as 
by  the  new  gold;  casting  the  gold  solders  or  twenty-two  karat  plate  always  made  a  ragged  edge  which 
I  could  not  handle,  and  in  the  effort  to  polish  it  up  I  often  opened  up  a  very  much  larger  lap  joint 
than  I  had  planned  to  have. 

I  want  to  thank  all  the  gentlemen  for  their  courtesy  and  to  assure  them  that  the  field  is  just  merely 
opened.  I  have  only  touched  one  little  corner  of  it.  I  think  it  is  a  field  primarily  of  mouth  classi- 
fication which  we  dentists  simply  must  know.  We  must  know  our  environment,  we  must  know  it 
just  as  much  as  the  physician  knows  his  environment.  We  can  not  get  on  by  putting  in  three  or  four 
types  of  filling  just  because  it  is  the  thing  to  do,  but  we  must  study  our  mouth  environment,  and  per- 
sonally I  know  my  results  will  be  better.  I  hope  this  paper  will  be  torn  to  pieces  if  it  is  wrong,  because 
I  want  it  to  be  right. 


SOME  PRACTICAL  POINTS  ON  INLAYS 

By  L.   E.  Custer,  A.M.,  D.D.S.,  Dayton,  Ohio. 

CONDITIONS    NECESSARY    FOR    UNIFORM    CASTING 

First  thing  necessary  is  an  investment — a  material  which  will  neither  shrink 
nor  expand  and  which  will  withstand  a  high  heat.  For  this  purpose  I  have  used  a 
material  composed  of  plaster  of  paris,  one  part,  and  highly  calcined  fire-clay,  four 
parts.  This  possesses  two  advantages  over  plaster  and  silex.  The  fire-clay  having 
been  burned  at  a  much  higher  heat  than  that  used  in  casting,  does  not  shrink  during 
the  latter  act.  It,  moreover,  possesses  a  valuable  feature  over  silex.  If  silex  is 
examined  under  a  microscope  it  will  be  found  to  present  a  smooth  glass-like  fracture, 
whereas  the  fire-clay  particles  present  a  rough  and  somewhat  porous  surface.  The 
advantage  is  obvious.  The  plaster  ingredient  in  the  mixture  should  always  be  as 
little  as  possible  and  a  mix  of  fire-clay  and  plaster  will  contain  less  plaster  for  a  given 
strength  than  a  like  mix  of  plaster  and  silex.  A  cubic  inch  of  the  above  when  brought 
to  a  red  heat  will  shrink  scarcely  a  thousandth  of  an  inch,  therefore  the  shrinkage  of 
the  average  inlay  mold  would  only  be  about  one-fifth  cf  that — too  little  to  worry 
about. 

The  second  factor  is  the  condition  of  the  mold  at  the  time  of  casting.  It  should 
be  thoroughly  dried  and  raised  to  practically  the  same  heat  each  time  before  casting. 
If  the  investment  has  not  been  thoroughly  dried  out  steam  will  form  at  the  moment 
of  casting  and  prevent  perfect  filling  of  the  mold.  It  is  important  to  heat  the  in- 
vestment quite  hot  so  that  any  decomposition  cf  the  plaster  will  have  taken  place. 
If  the  gold  is  cast  into  an  investment  which  may  have  been  dried  out,  but  which  has 
not  been  heated  up  quite  well,  a  slight  decomposition  of  the  plaster  is  produced  at 
the  moment  of  casting  and  an  imperfectly  filled  mold  is  the  result.  An  incidental 
advantage  is  also  found  in  casting  in  a  hot  mold — the  gold  need  not  be  heated  so  hot 
as  where  it  is  cast  in  a  cold  mold. 

It  is  important  to  always  heat  the  gold  to  as  near  the  same  degree  as  possible. 
Theoretically,  it  should  be  fiuid  till  every  recess  of  the  mold  is  filled,  and  >et  not  so 
hot  that  it  remains  longer  in  a  fluid  state.  Unless  the  gold  quicklj^  solidifies  after 
being  cast,  although  the  case  may  have  been  dried  and  well  heated,  the  plaster  will 
liberate  gas  under  melted  gold  and  an  imperfect  filling  will  result. 

The  gold  should  be  cast  under  the  same  pressure  each  time.  There  are  prac- 
tically only  two  methods  of  casting — compressed  air  and  centrifugal  force.  When 
compressed  air  is  used  (steam  and  gas  come  under  this  head)  it  is  important  to  always 
have  a  good  surplus  of  gold  so  that  the  edges  may  be  sealed  by  the  weight  of  the 
fluid  gold,  otherwise  air  will  leak  under  the  gold  and  ruin  the  casting.  The  surplus 
gold  in  this  case,  especially  where  the  basin  is  quite  saucer-shaped,  does  not  affect 
the  force  with  which  gold  casts  as  much  as  where  centrifugal  force  is  used.  There  is 
no  reason,  therefore,  unless  one  is  hampered  by  a  poor  heat,  why  a  good  surplus  of 
gold  should  not  be  used  when  casting  under  compressed  air.  Where  centrifugal 
force  is  employed  as  the  casting  agent,  the  conditions  are  different  and  here  it  is 
especially  important  to  use  about  the  same  amount  cf  gold  each  time,  allowing  only 
for  the  difference  in  the  size  of  the  fillings.     Having  once  ascertained  what  amount  of 


64  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

surjilus  gold  insures  a  perfect  casting  under  a  given  centrifugal  force  those  conditi(jns 
should  be  repeated  as  nearly  as  possible.  The  mold  is  easily  distorted  by  too  great 
a  head  of  metal  or  by  too  high  centrifugal  speed. 

APPROXIMAL   CONTACT 

No  feature  is  so  important  in  approximal  fillings  as  the  contact.  Heretofore, 
this  has  been  difificult  to  secure  in  malleted  fillings,  but  with  the  cast  inlay  it  is  quite 
easy,  and  if  the  cast  filling  had  no  other  points  of  advantage  this  would  be  one  to 
recommend  it.  The  wax  filling,  unless  there  has  been  ample  room  for  its  finishing, 
will  show  a  small  facet  where  it  touched  the  neighboring  tooth.  This  should  be 
rounded  out  with  wax,  or  as  I  prefer,  after  casting,  to  flow  a  small  bit  of  22  karat  gold 
upon  the  facet,  thus  contouring  it  out  with  hard  gold  at  the  point  of  contact. 

DO  NOT  DEPEND  TOO  MUCH  UPON  THE  ADHESIVE  PROPERTY  OF  THE  CEMENT  TO  RETAIN 

THE   FILLING 

There  has  always  been  too  much  faith  placed  upon  the  retaining  property  of 
the  cement.  In  order  that  the  operation  may  be  facilitated  the  walls  in  many 
cavities  that  might  be  prepared  almost  parallel  are  quite  funnel-shaped  in  principle. 
This  should  not  be.  Where  thin  walls  surround  the  cavity  it  should  be  kept  in  mind 
that  these  do  not  serve  well  to  retain  the  filling  and  unless  these  walls  are  protected 
upon  the  masticating  edge  they  will  soon  spring  enough  to  break  up  the  cemental 
attachment.  We  are  prone  to  gauge  the  retentive  property  of  a  cavity  by  its  mside 
form.  We  seldom  take  into  consideration  the  thickness  of  the  cavity  wall.  The 
loss  of  many  fillings  is  due  to  placing  too  much  dependence  upon  frail  walls. 

CEMENTING 

If  you  examine  a  metal  inlay  that  has  come  out,  as  a  rule  it  will  be  found  that 
the  cement  has  broken  its  attachment  with  the  tooth  substance  and  is  still  adhering 
to  the  gold.  This  was  probably  due  to  imperfect  drying  of  the  cavity  at  the  time  of 
setting.  The  cavity  walls  should  be  thoroughly  dried  to  insure  adhesion  of  the  cement 
thereto.  This  adhesion  can  be  very  much  increased  by  wiping  the  cavity  out  with 
a  little  of  the  cement  liquid  and  drying  just  before  setting.  This  seems  to  pre- 
pare the  surface  for  a  stronger  adhesion  of  the  cement.  We  have  seen  the  cement 
cling  to  the  instrument  rather  than  to  the  cavity  walls  at  times.  This  is  due  to  faulty 
drying  out  of  the  cavity.  If  it  is  difficult  to  secure  the  most  perfect  dryness  it  is  all 
the  more  important  to  use  the  liquid  method  before  setting. 


RESTORATION  OF  FRACTURED  ROOT  BY  THE  CASTING  METHOD 

By  J.  Maurice  Crosby,  D.D.S.,   Bradford,   Pa. 

Remove  the  fractured  portion  of  the  root,  attach  a  handle  to  the  outside  with 
wax,  or  better,  drill  and  tap  labial  surface  of  fractured  portion  and  attach  a  piece  of 
German  silver  anchor-screw  wire.  This  forms  a  very  secure  and  convenient  handle. 
Oil  the  inner  surface  of  the  fracture.  Make  a  stiff  mix  of  plaster  into  which  press 
the  fractured  part  of  root,  inner  side  downward,  to  get  an  impression.  When  set 
hard  remove  carefully.  Immerse  the  impression  in  water  and  fill  with  wax,  restore 
contour  of  labial  surface.  Remove  and  cast.  Adapt  to  the  root  in  the  mouth  with 
the  crown  post  in  proper  position.  Wax  the  inlay  to  post  while  in  the  mouth.  Re- 
move, invest  and  solder  post  to  inlay.  Replace  in  mouth  and  finish  with  band  and 
cap  as  for  Richmond  crown,  or  a  half  band  fitting  the  lingual  surface  may  be  made  of 
wax  in  the  mouth;  remove  with  inlay,  post,  and  cast  to  same. 


EXPERIENCE  AND  EXPERIMENTS  IN  DENTAL  CASTING 

By  J.   R.   Osborne,   D.D.S.,   Shelby,  N.   C. 

I  ha\e  chosen  a  subject  that  calls  for  considerable  employment  of  the  first 
personal  pronoun,  and  my  apology  for  so  doing  is,  I  believe  I  can  present  some  ideas 
I  have  on  this  subject  more  intelligibly  and  more  profitably  by  a  recital  of  my  own 
failures  and  my  own  successes. 

I  found  this  work  one  oi  difticulties.  There  are  a  great  many  things  about  it 
tiiat  are  fairh-  understood  now  tliat  were  ncjt  known  when  1  began  it,  eighteen 
months  ago. 

Forcing  molten  gold  into  a  previous!}-  prepared  mold  is  about  all  it  takes  to 
define  this  process,  but  it  implies  the  working  of  some  materials  not  so  tractable, 
and  the  employment  of  a  technic  not  so  "easy  as  falling  off  n  log." 

I  agree  with  Dr.  Taggart  that  "it  is  not  a  lazy  man's  work,"  but  not  in  his 
statement  that  it  will  "make  a  poor  dentist  a  better  one,"  any  further  than  to  say, 
it  might  and  it  might  not.  The  dentist  who  cannot  make  a  good  cement  or  a  good 
amalgam  filling,  for  instance,  would  not  be  the  one  to  succeed  in  the  casting  business. 

It  is  a  work,  too,  that  will  not  admit  of  a  neglect  of  detail.  Several  conditions 
must  be  met,  many  kinds  of  work  performed,  the  neglect~of  any  one  of  which  leads 
to  failure.  And  there  are  no  partial  failures  in  this  work.  All  failures  of  any  kind 
and  to  any  extent,  are  failures.  Nor  has  it  reached  the  stage  of  perfection.  When 
some  clever  fellow  tells  us  how  to  overcome  the  inHuence  melted  metal  has  on  the 
walls  of  our  mold  cavities,  then  it  will  be  about  time  for  us  to  make  proclamation 
that  we  are  at  or  very  near  the  goal. 

Those  of  us  who  have  worked  incessantly  and  earnestly  ha\e  o\'ercome  the 
other  difficulties  that  gave  us  all  so  much  trouble  when  we  first  embarked  in  this 
work.  Let  us  compare  notes  and  tell  of  troubles  and  see  how  nearly  we  are  together 
at  this  time.  When  I  began,  which  was  just  as  soon  as  I  could  get  a  machine  from 
the  Taggart  people  after  the  announcement  of  the  cast  inlay  was  made  in  February. 
1907,  I  found  among  other  troubles  waiting  for  me,  something  like  this: 

An  imperfect  machine. 

An  investing  material  that  brought  me  trouble. 

A  model  material  that  is  not  an  ideal  one  for  the  work. 

A  large  solid  cuji  that  caused  me  to  endure  hardness. 

First,  as  to  the  machine,  I  do  not  wish  to  say  that  the  Taggart  machine  is  im- 
perfect for  the  dentist  who  has  city  gas  to  mix  with  nitrous  oxide  gas  that  accom- 
panies the. outfit,  but  it  was  certainly  imperfect  for  me,  not  ha\'ing  this  gas,  and  of 
course  I  could  not  use  the  blow-pipe  side  at  all. 

I  calculate  a  poor  wretch  in  Hades  with  his  claws  cut  off,  and  a  poor  dentist  in 
a  town  without  illuminating  gas,  and  a  Taggart  machine  are  alike,  at  least  in  one 
respect — poorl}'  equipped  for  what  is  before  them.  But  I  had  to  cast  with  it  anyway 
ffor  I  had  purchased  it).  In  having  to  cast  with  it,  I  found  out  a  principle  that  has 
settled  the  casting  machine  question  with  me.  In  tr\  ing  to  break  the  joint  between 
the  machine  and  the  cup,  using  a  wet  in\estment,  I  made  a  good  cast  with  not  a 
pound  of  pressure,  so  far  as  pressure  from  the  gas  is  concerned.      My  mind  rex'erted 


66  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

to  the  time  many  years  ago  when  I  poured  molten  lead  into  a  green  cane.  The 
promptness  with  which  the  lead  returned  was  something  fierce,  and  left  me  with  at 
least  two  impressions,  one  on  the  inside  and  one  on  the  outside  of  my  head.  But 
laying  all  jokes  aside,  I  am  here  to  tell  you  that  in  my  opinion  that  same  force  that 
gave  me  the  sore  head  is  the  one  to  drive  hot  gold  into  the  mold  prepared  to  receive 
it.  I  say  this  after  I  have  had  experience  with  not  only  the  Taggart  machine, 
but  all  the  other  ones  of  any  prominence  and  a  lot  cf  the  toys  thrown  in.  I  had  a 
machinist  here  make  me  a  machine  after  m}'  own  ideas.  I  wanted  something  positive 
and  quick  and  now  I  am  on  Easy  street. 

I  have  used  all  the  investment  materials  on  the  market  and  have  found  them 
unsatisfactory.  A  perfect  one,  so  far  as  I  know,  remains  to  be  worked  out,  unless  Dr. 
Price  has  it  in  his  artificial  stone.  I  hope  he  has  it,  as  this  one  thing  will  be  a  stumb- 
ling block  until  it  is  removed.  The  trouble  is,  it  must  be  impervious  to  meet  some 
decided  requirements  and  not  impervious  to  the  extent  that  it  will  not  take  care  cf 


Figs.  1,  2,  3,  4  and  6 

the  air  contained  in  the  mold  previous  to  casting.  This  is  but  one  complexity  of 
this  complex  part  of  the  work.  I  thought  I  had  it  fixed  in  the  taking  of  a  perfect 
impression  and  running  a  model  of  the  tooth  and  cavity,  and  making  a  model  of 
oxyphosphate  cement.  This  gave  me  some  big  advantages  that  I  had  to  turn  down. 
Looked  good  to  me  that  I  did  not  have  to  remove  the  wax  model  from  the  cavity, 
as  troubles  more  than  some  folks  think  creep  in  just  here,  in  the  removal  of  the  wax 
from  the  cavity  in  the  tooth  in  the  mouth. 

Then,  again,  the  cement  model  comes  out  of  the  fire  in  better  shape,  with  less 
change,  than  any  of  the  materials  in  the  cup.  This  gives  us  a  great  advantage  in 
finishing  the  filling  out  of  the  mouth,  an  operation  that  the  patient  is  not  apt  to  find 
any  fault  with.  But  the  cement  is  too  dense  to  allow  the  escape  of  the  entrapped 
air.  I  fought  hard  to  sprue  in  a  way  that  I  could  overcome  this  one  fault,  but 
except  for  certain  pieces,  I  have  failed.  For  casting  a  shell,  this  is  the  ideal  way — 
using  a  cement  model  invested  with  the  wax. 

SEPARABLE   CUP 

I  conceived  early  in  the  game  that  the  large  cup  was  all  wrong,  in  that  it  is  large 
and  that  it  is  solid.  Wrong  because  it  takes  too  long  for  the  investment  to  dry  out. 
Wrong  because  there  is  always  a  residue  of  wax  enough  to  blacken  the  gold  and  often 
there  is  enough  to  do  a  lot  more  damage  than  that.  Wrong  because  wax  is  not  in  all 
cases,  in  fact,  in  few  cases,  an  ideal  model  material.  I  devised  a  cup  and  for  the 
last  twelve  months  I  have  used  it  with  great  satisfaction.  I  use  a  small  separable 
cup  and  have  changed  the  time  necessary  to  dry  out  an  investment  from  40  to  60 
minutes  to  15  minutes.  Two  halves  of  an  investment  will  dry  out  in  less  than 
half  the  time  required  for  a  solid  mass. 

One  of  the  beauties  of  this  idea  is,  I  can  use  a  model  material  that  has  many 
advantages  over  wax. 


EXPERIENCE  AND  EXPERIMENTS  IN  DENTAL  CASTING  67 

A  knowledge  of  how  to  sprue  is  essential  in  using  this  cup  if  you  wish  to  use  as 
hard  a  substance  as  cement  for  a  model.  I  have  often  used  amalgam  but  I  find  no 
advantage  in  it  over  cement  or  modeling  compound,  except  in  certain  cases.  It 
gives  a  clean  mold  and  of  course  a  clean  cast,  something  very  much  desired.  Seven 
minutes  to  set,  one  minute  to  warm  cup,  separate  and  remove  model,  and  seven  more 
minutes  to  dry  out  (using  a  properly  constructed  dr^'er)  and  I  am  ready  to  bet  on 
the  result. 

I  neglected  to  saj^  under  the  head  of  investing  material,  what  I  use  for  that. 
As  I  said,  I  have  used  all  the  leading  materials  and  have  experimented  a  whole  lot, 
but  none  has  served  me  so  well  as  the  impression  and  Investment  Compound  put 
up  by  the  Consolidated  people.  I  am  not  referring  to  the  investment  they  put  up 
for  gold  casting.  It  may  be  better  than  any,  but  if  it  is  I  do  not  know  it,  not  having 
tried  it.  Returning  to  the  cup  matter,  I  will  say  that  a  reference  to  the  cut  will 
help  you  to  get  an  idea  of  the  advantages  this  separable  cup  has  over  the  solid  one. 

Fig.  1.  The  larger  half  of  the  cup  on  the  crucible  former  with  sprue  and  model 
filling  in  position  and  ready  for  in\cstment. 

Fig.  2.  The  smaller  half  of  the  cup  which  is  not  placed  in  position  until  No.  1 
has  been  filled  with  the  investment. 

Fig.  .3.  The  sprue,  threaded  at  one  end  to  screw  into  the  crucible  former  in 
order  to  sprue  at  a  certain  height  to  break  investment  at  proper  place. 

Figs.  4  and  5.  The  cup  after  investing,  setting,  warming,  separating  and  re- 
moval of  model. 


SEPARATE  BASE  FOR  A  CAST  GOLD  INLAY 

By  F.  R.   Henshaw,   D.D.S.,  Indianapolis,   Ind. 

This  applies  to  those  compound  cavities  in  bicuspids  and  molars,  where  it  is 
extremely  difiicult  to  prepare  the  cervical  portion  without  extensive  waste  of  the 
labio-buccal  and  linguo-buccal  margins.  Prepare  the  proximal  portion  of  the  cavity 
so  that  it  will  draw,  regardless  of  the  occlusal  portion.  Make  wax  model  and  cast 
this  portion  of  the  filling.  It  is  easy  to  see  that  you  have  obtained  a  perfect  contact 
at  the  cervix,  which  is  the  crucial  point  in  any  inlay.  Set  this  portion  of  the  inlay  and 
prepare  the  occlusal  portion  as  for  a  simple  case.  Cast,  and  set  the  second  portion 
and  the  result  will  amply  reward  you  for  the  additional  labor. 


RESTORING  TEETH  FOR  CROWN  AND  BRIDGE  WORK  BY  CASTING 

By  C.  Jensen,  D.D.S.,   Mt.   Gilead,  Ohio. 

No  doubt  every  dentist  has  a  method  of  his  own  in  restoring  teeth  for  crown  and 
bridge  work,  but  I  think  the  most  simple  way  is  that  of  casting  by  the  following 
method :  First,  see  that  the  roots  are  in  a  good  healthy  condition,  then  prepare  canals 
for  pins,  place  pins  in  position,  warm  wax,  build  up  and  shape  wax  model  so  that  you 
can  fit  crown  over  same,  cut  down  wax  model  so  as  to  form  a  slight  shoulder  on 
which  crowns  rest:  this  can  be  done  after  casting,  if  desired;  withdraw  pins  with 
wax  model,  invest  and  cast,  using  Acolitc;  finish  up  cast  as  desired;  make  band 
as  for  ordinary'  gold  crown,  soldering  piece  of  gold  over  end  of  band.  Cement  cast 
in  position,  then  place  band  over  cast,  place  warm  inlay  wax  on  band,  have  patient 
bite  to  obtain  perfect  occlusion,  then  carve  up  cusp,  remove  crown  and  cast  cusp, 
finish  up  crown  and  cement  in  place,  and  you  will  ha\e  a  tooth  that  will  be  ser\Hceable 
in  every  way. 


68 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


AIR  VENTS  IN  CAST  WORK 

By  D.  D.   Smith,   D.D.S.,    Sandusky,   Ohio. 

The  first  question  asked  when  the  cast  inlay  came  into  use  was,  "In  mailing 
the  cast,  where  does  the  air  get  out?" 

We  know  that  the  air  dees  not  always  get  out. 

My  object  is  to  show  a  few  ways  to  overcome  this  trouble.  .Some  have  been 
using  a  sprue  wire  from  the  base  of  the  investment  and  not  allowing  it  to  come 


-WAX 


,-^.4-^.---— -ASBESTOS  ROPE 


n  direct  contact  with  the  impression,  but  withdrawing  it  a  little.      In  these  cases  the 
gold  is  apt  to  blow  or  suck  through  and  thereby  make  a  failure. 

If  a  little  asbestos  rope  (about  the  size  of  an  engine  drill)  be  dipped  into  hot 
paraffin  and  allowed  to  cool,  it  will  be  of  great  service  in  forming  air  vents  in  cast 
work.  Pour  up  as  usual  and  while  the  investment  is  still  soft  insert  the  asbestos 
rope.  The  wax  will  make  the  asbestos  easier  to  handle  and  burns  out  when  heated, 
leaving  a  porous  passage  for  the  escapement  of  air  and  gases. 

The  asbestos  may  come  in  direct  contact  with  the  inlay  wax. 


METHOD  OF  OBTAINING  A  SHEET  OF  INLAY  WAX  SUITABLE  FOR 
USE  AS  A  BASE  PLATE 

By  Newton  W.   Hiatt,  D.D.S.,   Marion,   Ind. 

The  inlay  wax  is  melted  in  small  cup,  so  that  the  depth  of  wax  is  about  three- 
fourths  {^i)  of  an  inch.  A  small  round  vial  is  then  filled  with  cold  water  and  soaped 
well  on  outside.  The  thickness  of  wax  depends  on  the  number  of  times  the 
vial  is  dipped  into  the  wax.  It  should  be  dipped  quickly  each  time.  After  accumu- 
lating the  required  thickness,  the  wax  on  bottom  of  bottle  should  be  trimmed  ofif, 
and  a  warm  knife  run  through  the  wax  the  long  way  of  the  bottle,  when  the  wax 
will  come  off  very  easily.  By  warming  this  in  warm  water  it  may  be  adapted  to 
any  shaped  model,  and  removed  and  cast  as  any  inlay  or  crown.  The  object  of 
the  cast  plate,  which  is  particularly  adapted  to  the  lower  partial  plates,  cast  in  full, 
or  with  the  use  of  the  lingual  bar,  is  to  avoid  the  making  of  metal  dies,  which  in 
some  cases  is  very  difficult,  and  even  when  the  metal  dies  arc  ol)tained  it  is  .sometimes 
very  hard  lo  swage,  on  account  of  the  gold  buckling.  'Hie  cast  plalc  (ucrconies  all 
this,  and  can  be  made  to  fit  any  model  perfectly. 


THE  MAKING  OF  SOLID  AND  HOLLOW  WAX  DUMMIES  OF  THE 
BICUSPID  AND  MOLAR  TEETH 

By  T.   C.   Hutchinson,   D.D.S.,  Decorah,   Iowa. 

The  art  of  casting  inlays,  bridges,  and  the  like,  with  the  aid  of  pressure,  has  de- 
veloped a  great  many  ideas,  and  to  the  dentist  whose  inventive  genius  is  given  sway, 
who  thinks  and  works  out  new  possibilities  to  enable  him  to  do  his  work  more  easily, 
more  rapidly  and  more  perfectly,  the  invention  is  of  incalculable  value. 

With  the  advent  of  the  cast  inlay  comes  the  cast  bridge,  which,  in  my  opinion, 
will  eventually  supersede  the  soldered  bridge  for  posterior  teeth,  as  did  the  inlay 
displace  the  gold  filling. 

A  great  many  dentists,  in  fact  I  may  say  the  majority  of  them,  have  given  but 
little  of  their  attention  to  bridge  work.  It  is  a  continual  surprise  to  me  to  learn 
from  time  to  time,  as  I  have  done,  how  many  of  my  fellow  practitioners  overlook 
this  very  vital  branch  of  our  profession,  the  rebuilding  of  lost  teeth.  Nor  can  I 
understand  it,  for  it  has  been  my  experience  that  no  work  I  can  do  for  a  patient 
elates  him  more  or  gives  him  greater  comfort  than  to  supply  lost  teeth  by  bridge 
work.  You  will  make  a  friend  of  any  one  for  whom  you  can  do  artistic  and  service- 
able work  along  restoration  lines. 


Fig.  1 

For  the  average  dentist  this  work  should  be  easy  to  accomplish,  since  casting 
is  now  at  hand,  and  with  the  aid  of  a  Hutchinson  Bridge  Die  Plate,  for  making 
wax  models  of  the  buccal  and  occlusal  surface  of  the  bicuspid  and  molar  teeth,  he 
will  have  no  difficulty.  The  plate  contains  one  hundred  fifty-eight  molds  of  said 
teeth,  in  singles,  and  united  in  twos  and  fours,  giving  ample  variety  to  meet  all  cases. 
The  teeth  have  true  tooth-like  appearance  of  the  buccal  and  occlusal  surface,  with 
perfect  alignment,  and  but  a  few  minutes'  practice  will  enable  one  to  make  a  wax 
model  and  adapt  it  to  the  plaster  model  on  articulator  and  get  perfect  occlusion. 

Make  your  abutments,  take  the  impression  and  bite  as  usual  and,  placing  your 
models  on  the  articulator,  select  a  suitable  mold  on  the  plate  for  your  case.  If  you 
want  to  make  a  solid  gold  dummy,  take  sheet  wax,  soften  with  hot  water  or  a  flame, 
roll  to  the  size  needed,  then,  having  previously  wet  the  mold,  press  the  wax  into  it 
with  your  thumb,  pressing  it  in  as  far  as  you  can,  then  take  a  blunt  pointed  stick  and 
continue  the  pressing  until  3'ou  have  forced  the  wax  to  the  extreme  depth  of  the  mold. 
(Be  sure  to  see  that  the  wax  reaches  the  bucco-occlusal  points  of  the  mold.)  Then 
finish  with  the  thumb  pressure.  With  a  hot  spatula  or  flexible  knife  trim  off  the 
surplus  wax  from  the  mold.  Lift  the  model  out  and  you  will  have  a  pertect 
tooth-like  wax  (lumm>-.  Sec  Fig.  1.  ("ool  the  wax  dumnn-  in  cold  water  and  trim 
it  to  fit  between  abutments  on  artii  uLitor.  ()!itain  the  alignment  (the  heat  of  the 
fingers  will  soften  the  wax  so  that  nou  can  btiul  it  lo  an\  desired  sha|)e),  then  with 


70 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


the  hot  air  s^-ringe  heat  the  occlusal  surface,  close  articulator,  thereby  getting  oc- 
clusion, or  with  a  knife  jou  can  cut  here  or  there  as  is  needed  to  make  occlusion 
perfect.     See  Fig.  2. 


Fig.  2 


To  make  a  hollow  wax  model,  select  mold  from  the  plate  and  then  take  sheet  wax, 
soften  as  above  and  press  into  mold  with  your  thumb  as  far  as  you  can,  then  with 
soft  vulcanite  rubber  press  slowly  and  steadily,  heating  the  wax  occasionally,  but  be 
careful  not  to  get  the  wax  too  soft  as  it  will  tear  just  as  easily  as  though  it  were  too 
hard.  Heat  it  just  enough  to  make  it  elastic.  See  Fig.  3.  Trim  off  the  surplus 
wax  and  fit  to  articulator  as  above.  Cool  and  cast,  and  solder  22k.  plate  on  back, 
completing  your  hollow  dummy  You  can  gauge  the  thickness  of  the  metal  by  the 
thickness  of  the  wax  used. 

Should  you  want  to  use  porcelain  facings  on  part  of  the  dummy,  cut  off  the 
buccal  surface  of  wax  tooth  or  teeth,  having  previously  backed  your  facing  and  oiled 
the  pins.     Then  force  the  facing  to  place,  solder  the  backing  to  the  wax  with  hot 


P 


Fig.  .3 


Fig.  4 


spatula  and  on  the  occlusal  tip  solder  with  sticky  wax,  bringing  wax  over  occlusal 
point.  Then  remove  the  facing  (note  how  easily  it  comes  off)  and  place  No.  8  or 
No.  9  carbon  points  in  pin  holes  and  cast.  Drill  the  carbon  out  of  the  pin  holes,  and 
cement  facing  to  place.      (These  carbon  points  are  carried  by  the  dental  dealers.) 

It  is  ad^'isable  to  make  your  abutments  and  dummies  in  separate  cast  and  solder 
together. 

When  you  have  used  the  ai:iovp  method  of  making  posterior  bridge  dummies 
I  tliink  you  will  agree  \\ith  mc  that  you  have  made  your  last  soldered  bridge. 


LATEST  DEVELOPMENTS  IN  THE  CAST  GOLD  PROCESS 

By  Albert  L.  Le  Gro,  D.D.S.,  Detroit,   Mich. 

The  fundamental  principles  underlying  the  process  of  casting  gold  will,  in  ni\- 
mind,  ever  remain  the  same  and  it  is  not  the  latest  developments  in  the  process  that 
interest  the  practitioner  of  dentistry  most,  but  the  latest  developments  in  technique 
and  with  the  permission  of  your  honorable  committee  I  will  treat  the  subject  from 
that  standpoint. 

It  is  not  my  purpose  to  write  of  the  advantages  that  accrue  to  the  average 
dentist  should  he  adopt  the  method  of  casting  gold  fillings  in  his  practice,  for  I  assume 
that  from  its  very  incipiency  even  the  most  skeptical  were  quick  to  see  how  it  would 
revolutionize  certain  operations  for  good  in  the  profession. 

At  this  stage  in  the  development  cf  appliances  by  manufacturers  it  is  a  matter 
of  little  consequence  which  machine  you  select,  though  in  my  mind  there  is  a  dif- 
ference which  I  will  endeavor  to  show  you  later. 

I  have  always  advocated  strict  adherence  to  one  method  until  that  particular 
method  had  been  mastered  or  found  b^'  personal  experience  to  be  inadequate.  If 
3'ou  are  using  one  machine  and  your  neighbor  is  using  another,  it  does  not  necessarily 
follow  that  because  your  neighbor  is  getting  better  results  than  you,  that  his  machine 
is  necessarily  to  be  credited  with  his  success. 

In  a  majority  of  cases,  it  is  a  matter  of  your  neighbor  mastering  his  machine 
earlier  and  at  the  same  time  developing  a  technique  that  is  more  careful  and  com- 
plete than  yours. 

Analagous  cases  are  presented  in  ether  lines  of  machinery,  such  as  automobiles, 
for  instance.  Two  men  ma^'  have  identical  cars,  one  runs  his  with  a  minimum  amount 
of  upkeep  and  trouble  and  the  other  is  always  in  trouble  and  finds  that  his  wa^'  of 
taking  care  of  and  running  his  car  is  causing  the  expenditure  of  a  large  amount  of 
money  as  well  as  time.  I  merely  mention  this  to  show  that  the  man  who  is  having 
trouble  with  a  certain  casting  machine  is  b}.-  no  means  in  an  anomalous  or  unique 
position.  He  certainly  has  seen  or  heard  of  beautiful  castings  made  by  the  same 
make  of  machine  that  he  possesses,  so  the  natural  supposition  is  that  he  has  left 
some  little  detail  out  in  the  process  of  casting  which  brings  about  his  failure  and  he, 
not  the  particular  machine,  is  to  be  blamed. 

IXL.A.Y   w.\.\ 

Before  going  into  the  subject  of  technique  I  would  like  to  give  you  the  results  of 
my  inquiries  as  to  what  ingredients  should  enter  the  make-up  of  a  perfect  inlay  wax. 
I  have  found  that  a  combination  of  gum  dammar,  carnabaucr  and  parafifin  in  the 
proper  proportions  will  made  an  ideal  inlay  wax  that  can  be  car\-ed  like  a  fine  grade 
of  clay  without  distorting,  attendant  fracture,  or  the  use  of  warm  instruments,  a 
method  to  be  deplored  and  forever  banished  in  trimming  wax  inlays. 

All  except  the  parafifin  are  waxes  of  vegetable  origin  and  can  be  readily  volatilized. 
The  use  of  beeswax  should  be  avoided,  as  its  addition  even  in  much  smaller  quantities 
makes  a  much  softer  wax  which  is  more  difficult  to  car\e. 

Waxes  that  contain  animal  extracts  such  as  stearin,  spermaceta,  etc.,  should  be 
avoided  as  they  separate  from  the  compound  in  heat,  especially  in  a  flame,  and  they 


72  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

tend  to  make  the  wax  greas}^  and  flakey.  Carnabauer  is  the  hardest  and  highest 
fusing  of  the  waxes  and  is  added  to  give  the  wax  edge  strength  and  hardness,  and  to 
make  the  compound  higher  fusing.  The  gum  dammar  is  a  hard  translucent  gum 
which  gives  hardness  and  toughness  to  the  compound.  Dammar  overcomes  the 
tendency  to  flake  and  scale  which  is  characteristic  of  the  wax  compounds  containing 
paraffin.  The  addition  of  paraffin  makes  a  tough  plastic  compound  which  is  easier 
to  congeal.  A  small  quantity  of  ceracin  is  used  to  prevent  the  wax  from  being 
brittle  and  a  black  vegetable  coloring  matter  is  added  if  desired.  A  vegetable 
coloring  matter  is  recommended  because  it  leaves  no  residue  when  the  wax  is  burned 
out.  Green  should  be  avoided,  as  most  of  the  greens  which  are  usable  are  salts  of 
copper  and  poisonous.  There  is  a  great  difference  in  carnabauer  wax  on  the  market. 
Most  of  this  wax  is  imported  and  used  for  making  floor  waxes,  and  while  you  will 
find  some  that  is  hard  as  stone,  most  of  it  is  crumbly  and  cuts  more  like  an  inferior 
grade  of  clay.  The  best  grade  must  be  used  for  inlay  wax  as  the  quality  of  the  wax 
depends  largely  on  the  quality  of  the  carnabauer  used.  I  know  of  no  other  wax  on 
the  market  that  suits  me  so  well  as  that  manufactured  by  the  Ransom  &  Randolph 
Co.;  this  comes  very  near  to  being  just  what  we  want.  The  busy  dentist  has  little 
time  to  experiment  with  matters  so  small  even  though  he  should  be  thoroughly 
acquainted  with  the  ingredients  and  quality  of  same,  that  enters  into  the  make- 
up of  such  a  compound. 

That  I  may  more  clearly  explain  some  of  my  theories  as  to  cause  and  effect  in 
casting  gold  it  is  necessary  that  I  treat  of  the  crystallization  of  the  different  grades 
of  gold  and  the  metallurgy  of  that  metal  to  some  extent  also.  If  you  will  take  four 
nuggets  of  gold  of  18, 20, 22  and  24  karats  respectively,  and  bring  them  to  a  dancing 
molten  state  and  then  quickly  remove  the  flame,  you  will  notice  that  the  mass  of 
pure  gold,  in  crystallizing,  retains  practically  the  same  shape  in  a  crystallized  form  as 
it  did  in  a  fused  state.  The  22k.  will  flatten  some;  the  20k.  a  little  more  and  the 
18k.  will  be  perceptibly  flattened.  The  natural  deduction  is  that  the  molecules  of 
the  gold  in  the  24k.  have  the  greatest  tendency  to  retain  a  fixed  relative  position, 
and  as  you  go  down  the  scale  it  becomes  very  necessary  to  use  more  definite  pres- 
sure on  lower  grades  ihan  on  the  pure  in  casting. 

The  pure  gold,  the  melting  point  of  which  is  2012  degrees  Fahrenheit,  and  much 
higher  than  the  lower  grades,  necessarily  crystallizes  much  slower  than  the  others. 
About  30  seconds  is  necessary  for  the  complete  crystallization  of  pure  gold;  and  right 
here  I  would  like  to  tell  you  why  I  think  some  machines  are  better  than  others,  even 
though  beautiful  work  is  accomplished  with  any  of  them.  When  molten  gold  is 
forced  into  a  cavity,  whether  it  be  by  air,  centrifugal  force  or  steam  pressure,  each 
molecule  of  the  gold  used  is  supposed  to  have  a  definite  relative  position.  During 
the  first  few  seconds  in  the  process  of  crystallization,  pressure  should  be  definite  to 
accomplish  this,  not  increased  or  decreased,  and  some  means  should  be  furnished  by 
the  manufacturers  of  machines  that  admit  of  an  intelligent  understanding  by  the 
dentist  of  what  is  going  on  in  the  way  of  pressure  during  the  entire  process  of  crystal- 
lization. If  a  machine  is  not  constructed  on  those  lines  it  should  at  least  admit  of 
the  slight  increase  of  pressure  from  time  of  application  until  complete  crystallization 
has  taken  place.  In  experiments  conducted  by  myself  about  a  year  ago  I  learned  that 
a  definite  pressure  of  4  pounds,  if  absolutely  definite  during  the  entire  time  of  crystal- 
lizing, was  infinitely  more  accurate  than  those  that  ranged  from  30  pounds  down, 
with  no  fixed  pressure  at  any  time.  My  own  supposition  is  that  the  molecules  were 
not  held  in  their  correct  relative  position  during  the  entire  period  of  crystallization 


LA  TEST  DEVELOPMENTS  IN  THE  CAST  GOLD  PROCESS  73 

and  though  the  inlays  were  just  as  perfect  to  the  naked  eye,  they  did  not  fit  into  the 
cavity  with  the  nicety  that  the  one  of  4  pounds'  definite  pressure  diti.  H\en  greater 
discrepancy  is  shown  in  the  use  of  different  grades  of  g<jld.  The  common  allo\s  of 
gold  are  silver  and  copper,  either  one  of  which  tends  to  make  the  gold  more  sluggish 
than  the  pure  gold.  The  lines  in  the  finished  casting  of  an  allowed  gold  are  not  as 
sharp  and  it  is  therefore  not  deemed  advisable  to  use  anything  but  pure  gold  in  cavities 
of  extreme  shape,  for  it  is  a  rare  case  that  presents  no  defects  when  the  lower  grades 
of  gold  are  used.  If  alloyed  gold  must  be  used,  I  would  suggest  that  gold  alloyed 
with  copper  or  platinum  or  both  be  used.  Copper  does  not  materially  lessen  the 
malleability  of  gold,  while  at  the  same  time  it  hardens  it.  Silver  is  objectionable  at 
all  times  as  an  alloy  for  gold  that  is  used  in  casting.  It  has  been  recently  recom- 
mended by  some  well  known  dentist  on  account  of  the  color  produced,  but  it  is  a 
mistake  to  use  gold  alloyed  with  this  metal,  for  aside  from  making  the  gold  very 
sluggish,  it  has  little  edge  strength  and  will  not  make  what  I  call  a  perfect  inlay  in 
cavities  of  extreme  shape. 

With  a  little  experience  you  can  learn  to  distinguish  the  alloy  in  any  gold  com- 
bination on  sight.  A  yellow  tint  generally  indicates  equal  parts  of  silver  and  copper. 
A  red  tint,  an  excess  of  copper.  A  green  tint,  an  excess  of  silver.  One  of  the  most 
desirable  alloys  for  cast  inlay  work  is  composed  of  Gold,  22  Dwts.,  Plat.,  18  Grs., 
Copper,  3  Grs.  It  is  a  rather  difificult  alloy  co  produce  but  makes  a  sharper  casting 
than  any  other  I  have  been  able  to  find  as  there  is  very  little  oxidation  compared  with 
18,  20  and  22k.  golds  that  are  alloyed  with  silver  and  copper.  I  do  not  recommend 
this  alloy  for  its  ductility  or  malleability,  for,  like  most  of  the  alloys,  it  is  sadly 
deficient,  but  it  is  much  superior  to  gold  alloyed  with  silver  as  regards  color  and  will 
make  a  sharper  casting. 

In  regard  to  the  latest  developments  in  technique — there  are  a  multiplicity  of 
methods,  all  of  which  it  is  not  my  purpose  to  treat.  I  will  confine  my  remarks  to 
the  little  hints  that  my  own  personal  obser\'ation  and  experience  have  taught  me. 
As  you  all  know,  the  possibilities  of  this  work  are  only  limited  by  the  skill  and 
ingenuity  of  the  man.  So  many  different  possibilities  suggest  themselves  to  different 
men  in  this  work  that  it  would  be  presumptuous  on  my  part  to  attempt  to  tell  you' 
of  all  the  new  things  that  everyone  has  worked  ouc. 

In  the  May  and  June,  1908,  numbers  of  the  Items  of  Interest  are  two  very 
interesting  papers  by  Dr.  Price,  of  Cleveland,  which  are  well  worth  the  time  of  any 
dentist,  and  while  the  deductions  of  Dr.  Price  are  not  verified  by  my  own  personal 
experience,  there  is  much  of  interest  in  these  articles  that  show  thought  and  study. 
These  articles  come  the  nearest  to  working  out  the  problem  and  are  the  only  papers 
on  casting  gold  that  I  have  read  that  exhibit  an  intelligent  knowledge  of  the  condi- 
tions as  they  are. 

SECTIONAL   IXL.WS 

These  are  used  only  in  cavities  of  extreme  shape  where  the  caries  has  attacked 
the  tooth  to  such  an  extent  that  it  becomes  necessary'  to  retain  all  the  solid  tooth 
structure  that  is  left.  Take  a  cavity  in  a  large  molar  approximal  involving  the  oc- 
clusal angle  with  the  diameter  bucco-lingually  much  larger  at  the  cervical  than  at 
the  occlusal  portion.  The  cavity  is  so  large  bucco-lingually  at  the  cervical  portion 
that:  in  order  to  prepare  a  .solid  or  one-piece  inlay,  it  would  be  necessary  to  cut  dawn 
a  consi(k'ral)ie  pordon  of  good  solid  tootli  strurlure.  To  a\()id  tills  the  sectional 
inUus  or  t\\'o-|)ierr  inhns  arc  i'ni|)l()\'e(l.  These  inla\s  should  be  niadt'  hollow  l)\- 
carving  the  wax  inlay  or  b>-  the  use  of  suction  and  heat.      1  ha\e  been  using  a  suction 


7 A  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

apparatus  that  is  now  on  the  market  and  while  it  is  a  great  improvement  over 
the  carving,  it  is  quite  crude.  This  defect  will  be  overcome,  I  have  no  doubt,  as  the 
evolution  of  casting  gold  progresses  in  dentistry.  The  orifice  of  the  hollow  cavities 
should  be  so  carved  that  where  the  two  sections  are  in  place  the  cement  will  form  one 
solid  mass  running  from  the  hollow  in  one  section  to  the  hollow  in  another. 

Some  one  has  suggested  the  use  of  ethyl  chloride  on  cotton  for  chilling  wax 
inlays.  I  have  found  it  very  satisfactory  also  in  rubbing  a  smooth  surface  on  the 
outside  of  wax  inlays.  When  the  wax  inlay  is  removed  from  the  mouth  it  should  be 
washed  in  soda  water  to  remove  the  mucus  which  sometimes  produces  a  surface  on 
the  gold  inlay  that  you  cannot  account  for  otherwise. 

DITTMAR   CAST    SHELL    CKOWN 

I  shall  describe  the  Dittmar  method  for  casting  a  cast  gold  shell  crown,  for  I 
think  it  the  most  perfect  gold  crown  ever  constructed.  If  you  must  put  on  gold 
crowns  and  can  get  a  good  fee  for  them,  the  Dittmar  method  will  enable  you  to 
portray  nature  as  no  other  method  will  and  at  the  same  time  enable  you  to  construct 
a  crown  that  will  give  the  minimum  amount  of  irritation  to  the  gums.  After  the 
root  and  remaining  part  of  crown  have  been  ground  down  properly,  take  34  gauge 
pure  gold,  make  band  to  fit.  This  gold  is  so  thin  and  soft  that  an  absolute  fit  can 
be  burnished  slightly  under  the  gum.  Trim  band  proper  height  for  top  to  be  soldered, 
which  completes  an  ordinary  box  cap.  Have  the  top  and  band  fit  accurately  so  that 
the  minimum  amount  of  22k.  gold,  not  solder,  will  be  used  to  solder  the  two  together. 
I  recommend  22k.  gold  for  soldering  for  without  it,  the  gold  used  in  casting  will  melt 
a  lower  grade  of  solder  and  percolate  or  racher  be  forced  in  fine  films  up  inside  of  the 
band.  When  cap  is  completed  place  on  root  and  with  modeling  compound  in  a 
double  articulating  impression  tray,  take  the  bite  and  impression  at  the  same  time. 
Articulate  plaster  for  articulating  side  and  inlay  investment  compound  for  crown 
side  and  paint  the  adjoining  teeth  with  oil.  Now  heat  up  a  quantity  of  inlay  wax 
and  use  camel's  hair  brush  to  build  up  wax  on  the  cap  to  proper  contour  and 
articulation,  smooth  surface  with  chloroform,  saw  off  adjoining  teeth  and  then  the 
waxed  crown.  Invest  and  cast.  The  possibilities  here  are  great  and  most  beautiful 
work  can  be  accomplished. 

GOLD    AND   TIN   INLAYS 

To  use  an  inlay  made  of  a  layer  of  tin  and  over  it  a  layer  of  gold  at  first  thought 
seems  a  good  procedure,  but  the  only  argument  that  I  can  see  logical  in  its  favor  is 
the  economy  of  gold.  A  combination  tin  and  gold  inlay  can  have  no  other  par- 
ticular advantage  over  a  gold  inlay  for  the  layer  of  cement  must  come  between  the 
inlay  and  tooth  substance  and  all  the  arguments  used  in  favor  of  tin  at  the  cervical 
third  or  half  of  the  cavity  are  lost.  The  ideal  procedure  is  to  insert  the  tin  with 
pluggers,  burnish  the  top  and  then  make  a  cast  inlay  of  gold  to  finish  the  operation. 
To  make  a  combination  tin  and  gold  cast  inlay  is  somewhat  difficult,  at  least  it  has 
been  so  in  my  own  experience.  After  preparing  the  cavity  a  wax  inlay  is  made  of 
the  cervical  third  or  half  of  cavity.  The  top  of  this  wax  is  made  smooth  and  then 
oiled.  On  top  of  this  another  wax  inlay  is  made  to  come  flush  with  borders  of  re- 
maining portion  of  cavity  and  to  restore  occlusal  and  approximal  contour.  This 
part  of  wax  is  then  removed  and  cast,  leaving  the  cervical  portion  of  wax  still  in  cavity. 
When  the  occlusal  portion  is  cast  the  gold  is  heated  slightly,  placed  in  position  in 
the  cavity  and  then  withdrawn,  when  the  cervical  portion  or  remaining  wax  will  be 
seen  to  be  attached  to  the  gold  already  cast.     Now  comes  the  most  difficult  part  of 


LA  TEST  DE  VELOPMENTS  IN  THE  CAST  GOLD  PROCESS  7o 

the  operation.  Gold  has  a  great  affinity  for  tin  and  the  ilask  holcHng  the  in\est- 
ment  must  be  at  about  an  exact  temperature  to  cast  the  tin.  Tin  melts  at  442 
degrees  Fahrenheit  and  is  not  sensibly  volatile,  so  if  the  investment  is  heated  until 
the  wax  is  entirely  burned  out  of  the  investment  and  there  is  no  formation  of  gases 
continuing  and  then  allowed  to  cool  until  about  400  degrees  Fahrenheit,  melting  the 
tin  now  with  blow-pipe,  using  no  more  than  the  required  heat  of  about  450  degrees, 
a  successful  casting  on  the  gold  inlay  can  be  made. 

If  these  instructions  are  not  followed  out,  the  gold  under  a  greater  degree  of  heat 
will  entirely  absorb  the  tin  and  a  brittle  lead  color  mass  will  be  the  result.  Hydro- 
chloric acid  must  not  be  used  under  any  circumstances  to  pickle  the  filling  as  tin 
dissolves  in  the  acid  with  the  evolution  of  hj'drogen  and  formation  of  Stannous 
Chloride. 

COMBINATION    GOLD    AND    PORCELAIN    INLAYS 

One  of  the  most  satisfactory  operations  in  large  restorations  is  the  gold  inlay 
with  porcelain  face  baked  in.  The  inlay  is  made  in  the  usual  way,  preferably  with 
platinum  alloyed  gold.  The  wax  inlay  is  carved  out  or  sucked  out  with  heat  and 
air  on  the  wax  corresponding  with  the  portion  to  be  restored  in  porcelain,  with 
undercuts.  After  the  inlay  is  made,  Jenkins  porcelain  is  baked  in  and  an  esthetic 
result  is  accomplished.  Before  baking  in  the  enamel,  place  gold  inlay  in  cavity, 
burnish  borders  and  reduce  line  of  gold  on  exposed  border  between  margin  and 
cavity  for  porcelain  to  a  minimum  so  that  the  line  of  gold  will  be  almost  imperceptible 
when  work  is  finished. 

PORCELAIN  CROWN  WITH  CAST  CAP  AND  DOWEL  FOR  BADLY  BROKEN 
DOWN   ROOTS 

This  is  a  branch  of  the  work  of  Drs.  F.  Ward  Hewlett  and  C.  J.  L^'ons,  of 
Jackson,  Mich.  They  have  worked  together  practically  in  producing  a  technique 
that  gives  very  fine  results  in  these  extreme  cases  of  badly  broken  down  roots.  I 
first  saw  the  work  of  both  these  gentlemen,  introduced  at  Indianapolis,  early  last 
year,  and  after  mastering  it  to  some  extent  have  gotten  very  satisfactory  results  in 
my  own  practice.  An  article  on  the  subject,  with  detail  drawings  by  Dr.  Howlett, 
appeared  in  the  January  issue  of  The  Dental  Summary.  Every  dentist  should 
read  it.     I  will  give  briefly  the  technique: 

HOWLETT'S   CROWN 

A  bite  is  taken  over  the  abutment  to  be  crowned  with  Stent's  modeling  com- 
pound, which  is  very  hard  when  cold.  The  compoimd  is  then  carved  to  fill  the  space 
and  imitate  the  crown  to  be  restored.  A  thin  platinum  matrix  is  then  swaged  to  the 
occlusal  surface  of  the  tooth  which  has  been  built  up  and  carved  from  the  compound. 
This  matrix  is  then  removed  from  the  carved  tooth  and  filled  with  porcelain  by  a 
series  of  bakings  which  results  in  a  cap  of  porcelain  such  as  might  be  stamped  from 
gold  in  the  die  plate  for  a  gold  crown  or  bridge  dummy.  A  second  matrix  of  plat- 
inum is  made  on  the  root  stump  or  abutment  and  porcelain  built  onto  it,  restoring 
a  considerable  part  of  the  tooth.  This  is  then  placed  on  the  stump  in  the  mouth 
and  the  occlusal  part  of  the  crown  first  made  is  wa.Ked  on  top  of  it  and  the  patient 
forces  it  to  proper  occlusion  while  the  intervening  wax  holds  the  two  sections  of 
porcelain  together  and  in  place.  The  crown  is  then  removed  from  the  mouth  and  a 
portion  of  the  wax  removed  and  replaced  with  porcelain.  Then  the  rest  of  the  wax 
is  removed  and  the  space  filled  with  porcelain  and  the  whole  crown  is  fused  together 
into  one  piece. 


7G  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

lyon's  crown 
Dr.  C.  J.  Lyon's  crown,  which  differs  somewhat  from  that  of  Dr.  Hewlett's, 
though  the  fundamentals  are  practically  the  same,  is  a  porcelain  crown  with  cast 
cap  and  dowel  for  badly  broken  down  roots.  Use  iridio-platinum  post  gauge  20  as 
a  matrix  for  carrying  wax  inro  the  root,  letting  the  wax  extend  over  the  gingival 
margins  of  the  root.  This  should  then  be  carved  to  form  a  plate  for  the  crown;  a 
square  post  should  be  formed  in  wax  about  5  millimeters  long  and  set  in  the  middle 
of  the  plate  for  the  reception  of  the  crown.  The  wax  model  of  the  cap  and  dowel  is 
then  cast  in  pure  gold  with  the  iridio-platinum  wire  in  the  center,  after  which  it  is 
polished  and  set  in  the  root.  A  platinum  matrix  is  next  made  of  the  plate  and  post 
by  forming  a  tube  for  the  post  and  soldering  to  a  square  piece  of  platinum;  after- 
wards it  is  burnished  to  a  perfect  adaptation  to  the  plate  and  post.  A  Davis  crown 
is  used  for  the  body  of  the  porcelain  crown  by  grinding  out  a  section  from  mesial 
to  distal  large  enough  to  accommodate  the  post.  This  is  waxed  in  position  over  the 
matrix  and  all  withdrawn  and  Consolidated  body  packed  around  the  matrix  and 
fused.  After  the  crown  is  completed  the  matrix  is  removed  from  the  crown  and  the 
crown  is  cemented  to  the  cap  and  dowel. 

BRIDGE   WORK 

Those  who  have  had  experience  in  casting  bridges  in  one  piece  will  agree  with 
me  that  it  is  entirely  the  wrong  procedure  and  especially  where  inlay  abutments 
are  employed.  There  is  no  known  investment  compound  that  when  set,  even  under 
perfect  conditions,  will  expand  enough  to  compensate  for  the  contraction  of  gold 
when  crystallizing.  It  is  therefore  necessary  to  cast  bridges  in  sections  and  solder 
together  in  order  to  get  exact  results. 

The  fallacy  of  casting  directly  onto  porcelain,  I  think,  is  quite  well  recognized. 
Such  methods  have  no  other  claim  to  general  adoption  than  that  they  are  an  "eas}' 
and  rapid  method  or  means  of  obtaining  a  result  which  cannot  be  wholly  successful." 
In  conclusion  I  will  say  that  it  has  not  been  the  object  of  the  writer  to  assume 
that  there  is  any  "only  way"  in  the  processes  of  casting  gold,  and  while  the  subject 
given  me  by  your  committee  is  not  one  that  I  could  possibly  stick  to  the  text  on, 
my  initial  object  will  be  accomplished  if  this  paper  but  serves  as  a  stimulus  to  bring 
out  many  instructive  facts  that  you  all  must  possess  on  this  subject. 

DISCUSSION 

Dr.  M.  R.  Muir,  Detroit:  Cast  gold  inlay  work  is  not  yet  two  years  old,  and  everybody  has  his 
own  little  ideas,  and  we  should  have  an  expression  from  everyone  here  tonight  who  has  had  any  ex- 
perience in  this  work.  1  hoped  to  have  some  specimens  to  show  you  tonight,  but  I  have  only  one  which 
is  a  practical  case  that  I  made  this  afternoon — a  bicuspid  crown  with  a  porcelain  face  in  it.  The  facing 
was  removed  and  gold  cast  with  lead  pencil  points  in  the  pin  holes  to  keep  them  open,  and  the  facing 
is  then  attached  by  cement. 

The  subject  of  Dr.  LeGro's  paper  must  necessarily  bring  out  the  results  of  his  own  experience, 
and  as  it  is  largely  original  it  is  of  much  more  interest  than  if  he  had  obtained  his  ideas  from  books 
and  magazines  to  which  we  all  have  access. 

The  latest  processes  in  cast  gold  work  are  being  developed  by  dentists  every  day  in  their  own 
ofifices  as  the  possibilities  of  the  work  done,  by  casting  gold  is,  as  the  essayist  says,  limited  only  by  the 
ability  of  the  operator.  There  has  been  comparatively  little  on  this  work  in  the  dental  journals  in 
the  last  eight  or  ten  months;  nothing  important  during  that  time  in  the  Items  of  Interest  or  the  Cosmos, 
with  the  exceptions  of  the  results  of  the  work  done  by  Dr.  Price,  as  given  in  his  splendid  articles  ap- 
pearing in  the  May,  June  and  December,  1908,  Items. 

The  seed  was  sown  by  Dr.  Taggart  when  he  addressed  the  Odontological  Society  of  New  York, 
just  two  years  ago  tomorrow,  giving  to  the  profession  the  results  of  his  labors  and  since  that  time  it  has 
taken  root  and  flourished  in  nearly  every  dentist's  office  in  the  country.  Numerous  kinds  of  machines 
have  been  designed  with  a  view  to  economy  and  the  use  of  the  cast  gold  inlay  has  been  unmercifully 


LA  TEST  DEVELOPMENTS  IN  THE  CAST  GOLD  J'ROCESS  77 

abused  by  some.  Dr.  Ilasley,  in  the  January,  1909.  hems,  says  that  some  of  the  machines  are  so 
far  removed  in  form  and  action  from  the  usual  workroom  apphances  that  until  seen  in  operation  they 
might  pass  for  caricatures.  One's  thumb  guarded  by  a  wet  rag,  has  been  found  sufficient  to  force 
molten  gold  into  a  mold  so  as  to  produce  an  acceptable  inlay.  Compressed  air,  steam,  gun  powder, 
inertia,  centrifugal  force  and  atmospheric  pressure  brought  into  action  by  an  exhaust  pump,  a  pill 
box,  a  child's  toy  tin  pail  swung  around  one's  head,  a  pair  of  tongs,  a  Yankee  clock,  an  old  fashioned 
coffee  mill,  and  a  hundred  and  one  such  like  devices  have  been  suggested  in  the  dental  journal  for  inlay 
castings.  Just  here  let  me  quote  an  expression  of  Dr.  Price:  "You  are  disappointed  just  in  pro- 
portion to  the  height  of  your  ideals."  Therefore,  I  would  say,  govern  yourselves  accordingly  in  select- 
ing a  machine. 

I  agree  with  the  essayist  in  advocating  a  strict  adherence  to  one  method  or  machine  that  you 
know  others  to  be  getting  good  results  with,  stick  to  it  yourself  until  you  get  results.  Exactly  the  same 
can  be  said  about  inlay  wax.  I  can  get  the  same  results  with  the  wax  I  use  that  you  can  get  with  the 
wax  you  use,  and  you  can  get  the  same  results  with  the  wax  you  use  that  I  can  get  with  the  wax  I  use, 
which  goes  to  prove  that  the  wax  for  you  to  use  is  the  wax  that  you  know  how  to  use. 

There  are  several  substitutes  for  pure  gold  which  might  be  used  in  casting  for  anything  but  inlay 
work.  My  experience  has  been  that  nothing  takes  the  place  of  pure  gold  for  a  perfect  inlay.  The 
only  argument  to  be  put  up  in  favor  of  the  alloy  or  any  other  material  that  might  be  used  is  economj', 
but  I  would  not  consider  that,  as  the  time  consumed  is  the  same  and  results  are  not  as  good,  when  alloys 
are  used. 

Sectional  inlays  are  often  employed  to  good  advantage  and  are  sometimes  necessary  to  avoid 
unnecessary  cutting.  If  there  is  an  undercut  and  the  overhanging  walls  are  good  and  strong,  fill  it 
with  cement  before  taking  the  impression.  After  the  sidewalis  and  margins  are  prepared,  if  there 
still  remains  decay  in  the  bottom  that  if  removed  would  make  an  undercut,  take  the  impression  and 
remove  the  decay  after.  A  great  many  are  of  the  opinion  that  grooves  placed  so  and  so  in  the  cavity 
and  in  the  inlay  for  the  cement  to  lodge  in  help  materially  to  hold  the  inlay  in  its  place,  but  I  believe 
that  the  less  cement  you  have  between  the  inlay  and  the  tooth  the  stronger  and  more  permanent 
it  will  be.     I  had  that  ground  into  me  by  Dr   Reeves  and  it  is  still  there. 

On  account  of  the  perfect  fit  obtained  with  the  cast  gold  inlay  by  burnishing,  in  certain  cases  with 
plenty  of  mechanical  retention  one  can  afford  to  sacrifice  sofne  of  the  strength  given  by  the  cement 
and  I  frequently  hollow  out  large  inlays  v/ith  the  Roach  suction  wax  carver  to  save  using  so  much  gold , 
or  to  make  a  layer  of  cement  over  the  pulp  to  protect  it  from  thermal  changes.  Your  inlay  will  lit 
better  and  give  better  satisfaction  if  you  will  clean  it  with  hydrofluoric  acid  after  casting.  A  porcelain 
face  may  be  baked  into  a  gold  inlay,  or  the  cavity  can  be  prepared  in  the  inlay  before  setting  and  after 
it  is  set  proceed  in  the  usual  way  to  make  the  porcelain  inlaj'. 

I  do  not  know  of  a  better  way  for  chilling  and  removing  wax  inlays  from  the  cavity  than  the 
following:  In  the  left  hand  hold  a  small  abscess  syringe  with  platinum  point  filled  with  cold  water 
and  with  the  right  hand  heat  the  end  of  a  piece  of  copper  wire  about  two  inches  long  over  a  flame  and 
insert  it  into  the  wax  inlay — immediately  then  put  a  stream  of  cold  water  on  the  wire  and  the  inlay — 
this  holds  the  wire  in  its  place.  The  water  all  going  directly  to  the  place  where  needed  and  the  point 
of  the  syringe  being  small,  the  amount  of  water  used  is  small.  While  cooling  the  inlay  with  the  left 
hand  pick  up  the  pliers  with  the  right,  grasp  the  wire  close  to  the  inlay  and  remove.  At  this  point 
clean  it  off  with  a  cold  air  blast  from  your  air  syringe,  using  from  10  to  20  pounds'  pressure.  To  remove 
the  inlay  from  the  wire,  heat  the  wire  in  the  center  over  a  small  flame  and  the  inlay  will  fall  off.  A 
good  wax  inlay  can  easily  be  spoiled  by  hooking  an  exploring  point  into  it  and  pulling  and  partly 
shoving  it  out  as  is  necessary,  especially  if  it  fits  tightly  as  it  should.  I  do  not  think  there  is  a  machine 
made  that  will  cast  a  plate  or  bridge  without  getting  some  shrinkage,  enough  so  that  it  will  not  fit; 
I  have  never  seen  any,  and  have  tried  it — unless  it  can  be  done  with  Dr.  Price's  artificial  stone.  He 
claims  great  things  for  that,  and  I  hope  that  he  will  be  at  our  February  clinic,  and  I  will  let  him  speak 
for  himself  at  that  time.  That  artificial  stone,  if  it  is  not  perfected  now,  I  think  will  be  some  day. 
and  will  be  the  only  method  of  casting  large  inlays,  plates  or  bridges.  A  bridge  can  be  cast  separately, 
the  dummies,  and  then  the  parts  soldered  together,  but  I  do  not  think  that  there  is  a  machine  made 
that  will  cast  a  large  bridge  or  plate  that  will  fit. 

Dr.  M.  L.  W.\rd,  Ann  Arbor:  There  are  two  points  that  the  essayist  brought  out  that  I  would 
like  to  emphasize.  The  first  and  most  important  one  was  in  regard  to  the  kind  of  gold.  I  was  of  the 
impression  some  time  ago  that  only  pure  gold  could  be  cast  successfully.  I  am  of  the  same  opinion  still 
so  far  as  most  fillings  are  concerned,  because  the  pure  gold  admits  being  finished  better  to  the  margins. 
I  am  not  certain,  however,  that  it  is  the  only  one  that  we  can  depend  upon  for  some  other  kinds  of 
work.  Day  before  yesterday  I  cast  a  practical  case  out  of  18K  gold  plate,  by  cooling  the  mold  down 
before  casting.     It  appears  to  me  that  the  great  trouble  is  not  entirely  with  the  shrinkage  of  the  gold 


78  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

but  in  the  manner  of  handling  it.  Everybody  has  an  idea  that  they  should  cast  inlays  into  a  hot 
mold  while  in  foundry  work  it  is  just  the  reverse,  and  so  far  as  I  can  see,  it  should  be  so  here.  Gold 
will  shrink  on  cooling,  but  it  will  shrink  much  less  if  cast  into  a  mold  cool  enough  to  be  handled  in  the 
hands,  than  it  will  if  it-is  cast  into  a  mold  that  is  glowing  hot.  I  believe  18,  20  and  22K.  plates  can  be 
cast  reasonably  accurately  into  abutments,  saddles,  etc  ,  and  there  will  be  little  more  shrinkage  if  any 
at  all  than  if  they  were  made  of  pure  gold.  Such  golds,  however,  will  not  make  nice  margins  for  fillings. 
If  the  gold  is  heated  with  the  ordinary  blow-pipe  the  whole  investment  is  usually  heated  much  too  hot. 
The  heating  of  the  gold  should  be  done  with  the  oxyhydrogen  blow-pipe,  using  a  small  flame  so  that 
the  investment  remains  cool.  Even  though  the  small  flame  is  used  with  the  oxyhydrogen  blow-pipe 
it  takes  only  a  few  seconds  to  melt  the  gold  to  the  proper  state  of  fluidity  I  cannot  speak  with  too 
much  emphasis  about  the  necessity  for  not  overheating  the  investment  and  the  necessity  for  casting 
into  a  cool  mold  if  we  get  the  minimum  amount  of  shrinkage  of  the  gold. 

Another  thing  of  importance  in  this  work  is  the  pressure  under  which  the  gold  is  cast.  I  have 
found  that  all  of  the  present  investments  are  too  weak  to  stand  sudden  high  pressures  and  those  that 
have  been  overheated  are  especially  weak.  Almost  all  of  them,  one  or  two  of  them  fundamentally 
strong  ones,  will  stand  open  flame  of  the  Bunsen  burner  from  eight  to  fifteen  minutes  without  a  great 
deterioration  in  strength,  though  every  minute  or  two  beyond  fifteen  minutes  seems  to  convert  it  into 
a  drj'  powder.  Another  thing  of  importance  in  the  casting  process  is  the  keeping  of  the  gold  at  the 
proper  condition  as  regards  fluidity.  All  of  the  golds  almost  lose  their  identity  after  being  cast  the  third 
time.  They  take  up  contamination  from  the  investment  in  the  form  of  iron,  and  iron  is  found  in  all 
of  the  investments  Gold  will  become  contaminated  from  the  blow-pipes  sufficiently  to  prevent  its 
casting  perfectly.  A  good  thing  to  correct  this  is  to  melt  the  gold  and  place  upon  it  gradually,  keeping 
it  melted  all  the  time,  equal  parts  of  potassium  nitrate  and  borax.  The  flame  should  be  directed  onto 
the  gold  from  one  side  until  it  is  melted,  and  little  by  little  add  the  potassium  nitrate  and  borax.  Usually 
three  or  four  minutes  is  sufficient,  but  if  it  is  desired  to  raise  the  karat  considerably,  it  will  take  some- 
what longer  than  this.  The  oxygen  supplied  by  the  potassium  nitrate  oxidizes  the  base  metals  and  they 
are  carried  away  'n  the  slag.  This  is  a  standard  dry  process  for  refining  gold  and  one  which  every  den- 
tist can  use  to  advantage  in  connection  with  the  casting  process.  It  is  both  clean  and  handy  and  is 
particularly  effective  in  removing  iron  as  well  as  many  of  the  other  contaminations  found  in  gold 
that  has  been  used  for  casting. 

Dr.  S.  Becker:  I  would  like  to  hear  from  some  one,  his  experience  with  Acolite,  which  I  have 
used  considerably  for  attaching  porcelain  crowns  to  badly  decayed  roots.  I  expected  to  find  something 
in  the  paper  on  this  material.  I  have  used  it  considerably.  In  fact,  I  have  not  put  on  a  Davis  crown 
since  June  without  either  a  gold  or  Acolite  fitting.  I  have  used  the  gold  for  large  crowns  once  or  twice, 
but  it  takes  so  much  gold  as  to  be  prohibitive.  Acolite  has  a  good  sharp  edge  but  has  no  strength. 
I  do  not  like  to  cast  gold  on  the  porcelain,  for  the  reason  that  we  are  liable  to  check  the  porcelain, 
because  of  the  difference  in  expansion  of  porcelain  platinum  pins  in  the  tooth  and  the  gold  used  in 
casting.  I  do  not  think  Acolite  has  been  generally  used  for  so  long  but  what  we  want  to  know  some 
more  about  it.  Many  people  cannot  afford  to  pay  for  the  gold,  especially  in  attaching  I-ogan  crowns, 
where  you  will  often  find  there  is  a  big  space  on  the  lingual  side.  I  have  filled  these  spaces  by  casting 
direct  to  the  porcelain,  and  with  the  Logan  crown  I  can  do  it  very  nicely  with  the  Acolite.  but  whether 
that  is  going  to  stand  I  am  not  prepared  to  answer. 

Dr.  Muir:  I  think  you  can  cast  just  as  well  on  porcelain  as  any  other  way,  but  I  do  not  think 
it  is  advisable.  I  do  not  think  it  is  necessary.  In'  the  first  place,  it  changes  the  color  so  much.  I 
have  cast  some  on  porcelain  and  have  never  cracked  a  tooth,  but  they  have  all  been  experiments,  as  I 
have  never  done  a  practical  case  in  that  way.  I  think  they  are  just  as  strong,  and  I  think  the  tooth 
has  more  and  better  protection  if  the  gold  is  cast  on  it  than  any  other  way.  I  do  not  see  any  necessity 
for  checking  a  tooth  while  casting  on  it.  but  don't  think  it  is  desirable,  because  it  is  liable  to  change 
the  color  too  much.  I  think  it  can  be  done  just  as  well  by  cementing  the  facing  after  the  casting  is 
all  complete. 

I  think  I  did  have  to  grind  the  crown  I  am  showing  a  little;  I  took  just  a  little  bit  off  the  gold 
and  ground  the  porcelain  a  little.  There  is  some  change  due  to  a  certain  extent  to  the  contraction  of  the 
gold.  I  do  not  think  there  is  any  machine  made  but  that  there  is  some  contraction.  In  an  inlay  for 
a  filling  that  can  be  taken  care  of  by  lapped  margins  and  you  can  burnish  it  down  so  that  you  cannot 
detect  the  margin,  but  on  a  curved  tooth  as  this  is,  you  have  to  grind  a  little  olT  to  allow  the  facing 
to  go  into  that  gold.  It  may  have  baen  due  to  the  shrinkage  of  the  gold,  and  it  may  have  been  due  to 
the  distortion.  I  did  it  hurriedly  because  I  wanted  to  get  it  ready  to  bring  over  tonight.  J  do  not 
think  that  is  any  argument  against  the  use  of  the  method,  because  that  tiny  bit  of  grinding  can  be  done 
with  the  articulating  paper. 


LA  TEST  DE  VELOPMENTS  IN  THE  CAST  GOLD  PROCESS  79 

Dr.  a.  W.  Dumas:  I  wish  to  speak  in  regard  to  the  advisabiUty  of  casting  gold  onto  porcelain. 
I  do  not  think  any  casting  machine  should  take  the  credit  of  a  successful  casting  of  that  kind,  the  credit 
should  be  given  to  the  operator,  who  first  heats  his  case  and  porcelain  to  the  same  degree  of  heat  as 
the  molten  gold,  because  otherwise  you  have  about  the  most  powerful  elements  in  nature,  heat 
and  cold,  in  contact,  and  unless  you  have  your  porcelain  heated  to  the  degree  of  your  gold,  you  are 
sure  to  have  trouble.  I  have  been  successful  in  many  cases  in  casting  upon  bare  porcelain,  but  I  think 
it  is  folly  to  take  such  a  chance.  I  think  it  is  wiser  to  take  a  piece  of  pure  gold  and  anneal  it  and  burnish 
it  over  the  tooth;  in  that  way  you  save  time  and  will  not  crack  your  porcelain.  The  cracking  of  the 
porcelain  I  think  is  due  to  the  platinum  pin  in  the  tooth.  I  believe  that  as  soon  as  the  molten  gold 
strikes  these  pins  there  is  an  expansion  of  the  pins  which  causes  a  fracture  in  the  tooth.  You  may 
take  a  Davis  crown,  and  you  can  cast  your  metal,  gold  or  Acolite  upon  it  without  removing,  cast  the 
whole  at  once,  and  the  metal  will  find  its  place  into  the  inside  of  that  crown  so  that  it  will  be  impossible 
for  you  to  take  it  out.  From  that  I  should  infer  that  the  cracking  of  the  porcelain  was  due  mostly  to 
the  expansion  of  the  platinum  pin  baked  into  the  tooth.  I  think  it  is  economy  of  time  and  everything, 
to  burnish  a  small  amount  of  gold  against  your  porcelain. 

Dr.  Muir:  The  credit  should  not  be  given  to  any  machine  for  casting  on  the  porcelain;  it  can  Le 
done  with  any  machine.  I  do  not  advise  anybody  to  do  it.  I  say  it  can  be  done,  but  it  is  not  desirable. 
If  you  will  heat  the  case  hot  enough  to  get  the  porcelain  so  hot  that  the  gold  will  not  check  it,  it  can  be 
done  in  any  machine.  The  facing  has  got  to  be  hot  for  the  same  reason  that  when  you  cast  on  plati- 
num or  cast  on  gold  plate,  they  have  got  to  be  hot  so  that  the  new  gold  will  fuse  onto  them,  and  it  will 
fuse  onto  them.  This  cast  that  I  passed  around  has  a  platinum  band.  You  cannot  expect  the  hot 
metal  to  unite  with  a  cold  metal;  the  inside  of  the  mold  has  got  to  be  hot. 

Dr.  C.  H.  L.^nu:  I  want  to  help  you  out  a  little  on  the  casting.  It  is  utterly  impossible  to  fuse 
any  kind  of  metal  to  a  piece  of  porcelain.  It  was  never  known  to  happen.  You  can  flow  it  over  a 
piece  of  porcelain.  Whenever  a  piece  of  porcelain  and  platinum  come  together,  the  difference  bctA-ecn 
the  shrinkage  and  the  expansion  of  the  porcelain  causes  the  porcelain  to  crack  from  the  stress  on  the 
pin.  If  you  look  at  a  piece  of  window  glass  upon  which  you  see  various  designs,  these  are  made  by 
putting  glue  over  the  surface  of  a  smooth  piece  of  glass  and  allowing  that  glue  to  dry,  and  in  doing  so 
it  rips  out  the  design.  You  can  never  fuse  onto  a  vitreous  glass  or  porcelain  a  metal  that  it  does  not 
change  the  same;  it  simply  rips  off  the  design.  It  is  far  stronger  to  cement  a  crown  onto  a  metal  base 
than  to  fire  it  on.  Every  Logan  crown  is  weak  in  that  respect.  Every  bit  of  porcelain  is  fused  in  the 
mass;  and  from  the  piece  of  metal  inclosed  we  will  always  have  stress  upon  it,  so  that  the  tendency  is 
to  burst  when  it  is  re-heated.  Cement  your  crowns  instead  of  fusing  them.  If  there  is  no  strain  upon 
a  piece  of  porcelain  it  will  stand  indefinitely  if  you  do  not  fire-crack  it.  If  you  fire  a  piece  of  porcelain 
on  a  metal  base  as  in  continuous  gum  work,  it  will  change,  carrying  the  metal  plate  with  it;  and  the 
fractures  are  not  enough  to  talk  about;  or  it  will  peel  off  and  leave  a  nice  shining  surface,  and  the 
thicker  the  metal  the  more  it  will  fracture.  To  prevent  fracture  by  the  heat  when  soldering  facings, 
before  the  gold  is  cold  take  a  piece  of  asbestos  fiber  and  cover  the  piece  so  that  it  cools  slowly  and 
it  will  not  fracture.  I  have  worked  this  hundreds  of  times  and  never  had  a  fracture  when  I  took  thai 
precaution. 

Dr.  LeGro:  I  do  not  think  that  the  dentists  have  any  intelligent  understanding  of  what  is  going 
on  when  they  are  casting  gold.  They  know  that  they  are  getting  results  but  do  not  know  what  the 
cause  of  it  is.  They  have  not  gone  into  the  metallurgy  of  gold,  or  effect  of  pressure,  and  that  is  some- 
thing that  we  have  got  to  get  an  intelligent  understanding  of  before  we  reduce  this  to  an  exact  science 
or  practice.  As  I  stated,  we  have  a  great  many  articles  published  in  the  different  dental  journals, 
there  is  but  one  man  who  has  written  a  scientific  paper  on  this  subject,  and  that  is  Er.  Price,  of  Cleve- 
land. Of  course,  he  is  in  a  position  to  go  into  this  scientific  research  more  than  the  rest  of  us.  I  am 
rather  disappointed,  therefore,  that  it  was  not  more  discussed  from  the  scientific  aspect.  However, 
I  expected  an  "experience  meeting,"  and  such  meetings  always  give  us  much  to  think  about. 


80 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


CAST  GOLD  CROWN 

By  C.   E.  Meerhoff,  D.D.S.,   Chicago,   111. 

Especially  adapted  for  bridge  abutments.  Trim  root,  fit  band  of  35  or  36 
gauge  platinum  (or  gold),  stove  pipe  shape.  Xip  end  of  bands  and  bend  over 
root.      (Fig.  1.) 


^^  ^9 


D 


i 


Have  patient  bite  into  wax,  giving  exact  articulation.     (Fig.  II.) 

Carve  to  correct  shape  and  with  bur  or  suction  remove  wax  from  inside  as 
desired. 

Pass  quickly  through  alcohol  or  Bunsen  flame,  or  rub  down  wax  with  chloroform 
to  finish  or  smooth  wax.      (F"ig.   III.) 

The  crown  on  model  has  not  been  touched  by  buffer  or  wheel. 

ADVANTAGES 
Strength — Thickness  of  metal  external  to  band  makes  crown  unbreakable. 
Definite  seat — Ease  of  adaptation  of  thin  metal  obviating  irritation  at  gingival. 


CAST  JOINTED  LOGAN  CROWN 

By  C.  J.  Burris,  D.D.S.,  Washington,  Ind. 

The  jointed  Logan  crown  is  by  no  means  new,  but  is  perhaps  being  used  more 
since  the  advent  of  casting.  It  is  especially  advantageous  in  cases  where  from  decay 
or  otherwise  the  tooth  structure  has  been  lost  to  an  extensive  degree  beneath  the  gum 
line. 

After  the  tooth  root  has  been  prepared  as  in  cases  for  the  Logan,  select  a  removable 
pin  crown  with  due  regard  to  size  and  shape  and  grind  to  a  joint  beneath  the  gum 
line  on  the  labial  surface  only.  Then  by  use  of  an  iridio-platinum  pin  join  the  two 
parts  with  inlay  wax  and  press  to  place  against  the  tooth  root.  Remove  and  trim 
away  the  surplus  wax,  replace  and  burnish  wax  around  the  tooth  root.  The  crown 
can  now  be  separated  from  the  pin  and  wax  and  the  latter  invested  and  cast  pref- 
erably by  the  use  of  pure  gold. 

This  method  gives  increased  strength  to  the  pin  as  well  as  the  adaptation  to 
the  root  surface;  the  parts  can  now  be  united  with  cement  and  when  finished  are  ready 
for  setting. 


THE  CAST  GOLD  INLAY 

By  James  W.  Lyons,   D.D.S.,  Jackson,   Mich. 

It  is  a  very  great  pleasure  for  me  to  appear  before  you  at  this  meeting,  one  of 
the  very  auspicious  occasions  in  the  history  of  this  society. 

I  am  pleased  to  give  you  the  best  my  feeble  ability  may  permit  on  this  subject 
which  has  interested  the  profession  of  the  world  and  centered  all  c^cs  and  thought 
upon  an  American  dentist  and  an  American  city. 

I  may  be  unable  to  ad\'ance  any  new  ideas,  but  I  might  present  some  thought 
in  a  light  that  some  one  may  be  benefited  in  the  use  of  this  method. 

It  is  but  just  to  give  credit  to  those  few  constructive  geniuses  that  are  found  in 
our  profession.  There  is  not  a  great  number  among  those  who  ha\e  taken  up 
dentistry  as  a  life  work  to  which  we  may  point  in  either  scientific  or  mechanical 
research  who  stand  out  pre-eminently  above  all  their  fellows,  but  our  ranks  are  full 
of  men,  clean-cut,  shrewd  and  wide  awake  to  every  progressive  step  forward  made 
by  the  other  fellow  and  are  capable  of  applying  the  ideas  and  either  simplifj'ing  or 
enlarging  upon  them,  cutting  and  trimming  away  the  corners,  or  rounding  them  out, 
thus  making  them  all  the  more  practical  and  useful. 

It  is  true  that  many  men's  lives  are  so  filled  with  work  that  they  do  not  have  the 
time  to  grasp  and  assimilate  or  even  to  try  out  the  many  valuable  methods  that 
are  created  for  their  benefit.  We  find  a  great  many  dentists  who  have  long  been 
accustomed  to  following  out  one  specific  plan  in  their  work.  They  ha%e,  of  course, 
learned  b}'  pursuing  this  plan,  to  do  their  work  well  and  comfortably  and  rather  dread 
to  get  out  of  the  rut  and  accept  anything  in  the  way  of  an  innovation. 

A  departure  from  the  use  of  foil  and  the  mallet  and  the  adoption  of  the  inlay 
requires  much  effort  on  the  part  of  many  dentists. 

Two  years  ago  I  had  the  pleasure  of  presenting  a  paper  on  the  gold  inlat'  before 
this  society.  It  is,  indeed,  remarkable,  the  progress  made  in  these  two  years, 
and  I  greatly  appreciate,  when  I  read  over  the  paper  I  prepared  at  that  time,  the 
importance  the  gold  inlay  has  established  among  our  many  valuable  fillin.g  materials. 

ADVANCE    BEING   M.ADE 

Do  you  comprehend  the  advance  being  made  along  mechanical  and  artistic 
lines  by  our  careful  and  observing  operators  today? 

To  keep  apace  with  the  times,  is  there  one  thing  that  makes  it  more  obligatory 
upon  us  than  to  get  out  and  come  in  contact  with  the  men  who  arc  doing  things? 
When  I  meet  and  talk  with  a  man  who  locks  himself  within  his  own  surroundings 
his  conversation  upon  dental  topics  has  a  like  bearing  to  the  knowledge  possessed  of 
current  affairs  b}'  the  man  who  never  sees  a  daily  paper. 

The  gold  inlay  came  to  us  because  within  our  minds  there  was  a  demand  for 
just  such  an  institution.  We  receive  from  mother  nature  many  inventions  at  just 
such  a  time  as  when  our  surrounding  conditions  demand  them.  Our  minds  become 
imbued  with  the  desire  to  accomplish  some  especial  purpose  and  by  concentrating 
thought  along  that  line  we  develop  that  for  which  we  are  stri\ing.  At  first  our  ac- 
complishment may  be  crude,  but  by  still  further  thought  and  l)y  the  application  of 
scientific  principles  it  Is  impro\ed  and  made  better. 


82  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Esthetic  appearance  brought  to  us  the  porcelain,  which,  be  it  beneficial  or  be  it 
detrimental,  our  enthusiasts  placed  in  all  cavities  regardless  of  location,  but  the  more 
conservative  man  felt  the  need  for  a  material  which  would  better  withstand  the 
battering  of  mastication. 

Manipulatory  skill  gained  with  the  burnishers  in  burnishing  the  platinum 
matrices  to  the  cavities  developed  the  idea  of  thus  shaping  a  matrix  and  flowing  it 
full  of  the  gold  and  employing  it  in  large  molar  and  bicuspid  restoi-ations,  by  such 
a  material  enhancing  the  value  of  our  operation  as  to  durability  and  overcoming 
the  friable  edge  of  porcelain.  With  this  inlay  of  gold  we  had  accomplished  much,  we 
had  rendered  inlay  work  more  practical,  and  we  had  achieved  much  to  better  our 
services  to  our  patient,  but  as  we  went  along  in  the  practice  of  these  methods  the 
only  thing  we  seemed  to  be  gaining  was  manipulation;  we  were  learning  to  make 
closer  adaptations,  we  were  studying  methods  of  producing  the  least  amount  of 
shrinkage,  methods  of  procuring  the  hollow  inlay  and  various  peculiarities  to  obtain 
an  ideal  form  to  get  the  most  perfect  restoration  of  lost  tooth  structure. 

When  the  time  became  ripe  it  was  left  to  Dr.  Wm.  H.  Taggart  to  bring  before 
the  profession  probably  the  greatest  achievement  of  the  present  century,  "The  cast 
gold  inlay,"  and  you  wonder  why  you  did  not  conceive  of  this  system  of  producing 
the  inlay,  but  as  I  have  said  before  in  this  paper,  we  find  the  results  of  concentrated 
thought  along  this  particular  line.  Dr.  Taggart  spent  many  weeks  and  months 
experimenting  before  he  developed  the  proper  idea  of  producing  that  which  he  sought. 
He  had  the  completed  product  in  his  mind  and  was  working  to  achieve  that  particular 
result  with  which  he  was  crowned  with  success. 

THE   CAST   INLAY 

The  cast  inlay  is  certainly  the  highest  ideal  in  the  gold  inlay.  At  one  great 
stride  Dr.  Taggart  placed  all  our  matrix  inlays  so  far  in  the  background  and  out  of 
date  that  they  will  never  be  resurrected.  What  an  ideal  method,  when  we  can  take 
a  piece  of  wax  and  shape  a  wax  filling  in  the  mouth,  restore  occlusion  and  contour 
in  its  most  minute  form  and  then  duplicate  that  in  gold  so  that  it  fits  the  cavity,  to 
absolute  accuracy;  it  is  most  emphatically  a  great  triumph  in  dentistry. 

The  method  is  but  just  in  its  infancy  and  yet  its  field  seems  unlimited.  Almost 
every  day  presents  some  phase  in  practice  in  which  we  can  apply  the  principle  with 
the  most  remarkable  and  gratifying  results. 

Besides  the  inlay  filling,  it  is  admirably  adapted  to  the  restoring  and  building 
up  of  badly  decayed  roots  for  the  purpose  of  crowning. 

Ideal  for  anchorage  of  small  bridges,  repairing  broken  Logans,  casting  cusps, 
dummies  and  for  a  multitude  of  uses.  Even  if  Uncle  Sam  would  just  guarantee  us 
to  keep  out  of  the  game  we  might  even  be  able  to  retire  from  the  practice  of  dentistry 
by  casting  gold  dollars. 

But,  ladies  and  gentlemen,  talk  is  cheap — just  wait  a  bit.  A  few  years  ago  we 
had  men  who  couldn't  find  a  cavity  but  what  it  came  under  the  indications  for  a 
porcelain  inlay.  They  even  seemed  to  look  upon,  with  scorn  and  contempt,  the 
operator  who,  a  little  conservative,  had  evidence  about  his  operating  room  that  he 
had  use  for,  sometimes,  gold,  tin  and  amalgam. 

Today  the  conservative  man  has  been  wise,  the  other  fellow  is  wiser;  if  he  isn't, 
some  one  else  has  his  patients. 

We  are  even  again  hearing  the  same  class  of  operators  who  always  grasp  a  new 
method  and  ride  it  to  death  as  a  hobby,  making  the  assertion  that  the  day  for  mal- 


THE  CAST  GOLD  I  NLA  V  83 

leting  in  gold  and  for  the  old  amalgam  arc  gone,  that  they  do  not  expect  to  make  use 
of  the  malleted  gold  filling  again. 

It  has  always  been  a  question  with  me,  upon  which  I  have  not  as  vet  passed 
decision,  whether  these  men,  faddists,  if  you  please,  are  really  a  benefit  or  a  detri- 
ment to  our  profession;  my  judgment  is  that  they  are  at  least  enemies  to  themselves. 

The  cast  inlay  method  is  a  great  achievement  in  art  and  mechanics  and  I  appeal 
to  you  all  not  to  abuse  it.  By  carrying  out  this  method  carefully  it  does  for  us  what 
no  other  method  ever  accomplished  to  the  same  extent.  Owing  to  the  absolute 
accuracy  which  you  must  obtain,  it  develops  in  you,  unconsciously,  a  high  degree 
of  skill. 

Gentlemen,  do  not  assume  the  idea  that  all  that  is  rccjuired  to  make  successful 
inlays  is  a  particlular  kind  of  machine.  Vou  have  much  to  learn  to  l)ecome  an  inlay 
worker. 

A  gold  filling  thrown  into  the  tooth  most  any  way,  pro\i(ling  you  happen  to 
have  two  opposing  angles  or  pits,  may  stay  long  enough  for  the  patient  to  move  out 
of  your  locality,  but  an  inlay  inserted  regardless  of  conditions  stays  a  mighty  short 
time. 

The  very  highest  art  and  skill  arc  demanded  in  cavity  preparation  for  inlays. 

I  believe  a  man  will  be  able  to  do  a  very  much  better  gold  filling  after  he  has 
done  inlay  work  for  a  time,  for  the  reason  that  his  training  in  the  thoroughness  of  his 
cavity  preparation  will  instill  into  him  the  idea  of  very  superior  formation  to  what 
he  has  been  accustomed  to. 

It  has  been  suggested  that  the  casting  of  fillings  might  have  a  tendency  to 
cheapen  our  operations.  Some  men  argue  that  as  it  is  easier  on  them  and  dees  not 
take  so  long  as  to  mallet  in  a  filling,  our  fee  should  be  less.  For  those  men  let  me  say, 
they  should  belong  to  the  union  labor  crowd,  where  they  could  operate  under  a  scale 
of  wages. 

It  is  too  burdensome  to  my  minfl  to  work  out  a  classification  for  such  men  among 
scientific  and  skillful  dentists. 

How  unfortunate  it  is  that  our  colleges  cannot  wake  up  to  the  fact  that  our  pro- 
fession needs  fewer  men,  and  iJiose  with  high  ideals,  and  not  great  numbers,  who  as 
failures  in  the  highest  arts  in  dentistry,  might  make  the  very  best  of  machinists  or 
blacksmiths. 

This  class  of  work  should  demand  the  closest  application,  plenty  of  time,  and  the 
best  of  your  skill,  all  of  which  call  for  the  best  of  fees. 

It  is  a  great  mistake  with  the  young  men  entering  the  profession  in  taking  up 
chc  inlay  as  an  easy  method  to  a  result,  thinking,  by  so  doing,  of  his  abandoning  the 
long,  tiresome  gold  filling,  when  their  experience  has  been  so  limited  as  to  be  unable 
to  discriminate  between  the  indication  for  filling  or  inla^-.  Their  manipulation  of 
filling  materials  is  needed,  their  judgment  and  observation  more  mature. 

You  will  find  your  patients  very  appreciative  of  a  method  which  restores  their 
broken  down  molars  and  bicuspids  so  excellently  to  usefulness,  with  so  little  incon- 
venience to  themselves. 

How  much  higher  the  ideal  as  compared  with  the  gold  crown  which,  at  its  best, 
is  so  ill-fitting  around  the  gingivae  which  nature  so  admirably  formed. 

How  perfectly  the  inlay  replaces  so  many  defective,  unsighth-  and  ofttimes 
poorly  adapted  amalgam  fillings.  While  amalgam  may  have  been  both  the  patient's 
and  dentist's  friend  in  sa\ing  some  pretty  bad  wrecks,  >ct  like  the  untrue  friend,  it 


84  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

has  been  the  cause  of  many  wrecks.  I  hope  we  may  be  able  to  eliminate  some  of 
these  failures  with  the  cast  inlay. 

I  do  not  approve  of  the  use  of  the  gold  inlay  in  the  anterior  teeth,  excepting 
where  great  stress  is  brought  to  bear,  as  in  end  to  end  occlusion,  or  in  opening  the 
bite  where  abrasion  has  cut  out  the  lingual  surfaces  of  these  teeth. 

The  work  is  very  exacting  and  tedious,  but  because  it  can  be  done  in  stages  it  is 
not  so  laborious  either  to  patient  or  operator  as  some  of  the  older  methods,  and  as 
far  as  my  observations  go,  the  end  to  be  obtained  is  nearer  reached  than  by  the  older 
method. 

We  are  all  amateurs  yet  in  the  handling  of  the  cast  gold  inlay,  and  finding  out 
every  day  that  there  are  things  yet  to  be  learned  which  our  conceit  had  attempted 
to  make  us  believe  we  knew  all  about. 

CAVITY   FORMATION 

The  first  step  as  with  all  inlay  work  is  cavity  formation,  which,  as  I  have  said, 
calls  forth  all  the  skill  and  ingenuity  that  the  best  operators  possess,  if  it  is  properly 
done.  The  plan  of  the  cavity  should  first  be  mentally  mapped  out  and  then  executed, 
if  it  takes  the  entire  time  for  one  sitting,  because  upon  the  proper  and  perfect  forming 
of  the  cavity  depends  the  success  of  the  inlay.  With  the  gold  inlay  it  does  not  re- 
quire the  sacrificing  of  as  much  sound  tooth  structure  as  it  may  for  the  porcelain. 

Force  and  direction  of  occlusion  must  be  taken  into  consideration  and  the  inlay 
set  so  that  these  forces  have  a  tendency  of  forcing  it  into  the  cavity  instead  of  out 
and  away  from  it. 

We  must  obliterate  all  undercuts  that  the  wax  may  be  drawn  from  the  cavity 
without  the  slightest  change  of  form.  By  slightly  diverging  walls,  angles  and 
beveled  grooves,  get  all  the  frictional  retention  j'ou  can. 

If  possible  to  get,  form  your  cavities  wedge  shape  with  flat  base  or  bases  bevel, 
converging  towards  the  pulp. 

The  pulpal  wall  should  be  as  parallel  as  possible  to  the  surface  of  the  tooth  upon 
which  the  cavity  is  located.  Saucer  shaped  cavities,  with  the  dependence  almost 
entirely  upon  the  cement,  will  fail  to  hold  an  inlay  for  any  great  length  of  time,  no 
matter  how  much  time  or  work  you  may  have  put  upon  the  inlay  itself.  Many 
discouraging  failures  in  inlay  work,  I  believe,  are  due  to  a  lack  of  knowledge  or  dis- 
regard for  these  principles. 

THE    WAX    INLAY 

The  next  step  is  the  wax  inlay.  I  believe  in  taking  a  good  generous  piece  of 
the  prepared  wax,  for  the  reason  that  small  portions  are  difficult  to  unite  after  they 
have  been  once  moistened  in  the  mouth.  Soften  the  wax  in  warm  water,  not  above 
138  F.  Do  not  apply  dry  heat  as  it  seems  to  make  the  wax  crumbly.  Now  press  wax 
to  place  in  the  cavity,  see  that  it  presses  closely  to  the  bottom  and  over  all  the 
borders,  then  have  the  patient  close  the  teeth  and  go  through  all  the  movements  of 
mastication,  as  just  the  mere  fact  of  shutting  the  teeth  together  does  not  give  us 
correct  occlusion. 

The  cavity  needs  no  other  lubricant  than  the  existing  moisture  of  the  mouth. 

After  getting  the  correct  occlusion  of  the  teeth,  I  begin  carving  away  surplus 
wax  and  also  with  flat  burnisher  work  the  wax  down  perfectly  to  and  over  all  borders. 
Asking  the  patient  to  open  the  mouth,  I  hold  the  wax  in  place  and  carve  and  shape 
contours;  then  by  means  of  cotton  pledgets  and  tape  moistened  with  liquid  vaseline, 
I  finish  and  polish  this  wax  inlay  until  it  is  just  as  near  my  idea  of  what  I  desire  in 


THE  CAST  GOLD  INLAY  85 

the  gold  as  I  can  get  it.  Very  often  I  lift  it  from  the  cavity,  chill  in  cold  water,  trim 
away  feather  edges  and  reset  in  cavity  two  or  three  times  before  I  have  it  completely 
finished  down.  When  I  consider  my  wax  inlay  complete  I  remove  and  attach  my 
little  sprue  wire.  I  prefer  doing  it  this  way  to  attaching  sprue  to  wax  in  the  cavity. 
Next,  adjust  sprue  to  the  little  crucible  former  and  proceed  to  invest.  This  is  another 
portion  of  the  technique  which  is  very  critical  and  wherein  your  success  hangs  in 
the   balance. 

INVESTMENT 

Your  investment  must  be  of  such  material  in  which  the  shrinkage  and  expansion 
shall  be  the  minimum  and  not  change  form  whatsoever  under  heat.  It  needs  to 
be  carefully  and  uniformly  mixed  and  I  have  the  habit  of  turning  my  plaster  bowl  on 
its  sides  and  revolving  while  mixing  until  my  investment  is  coated  all  over  the 
inside  of  the  bowl  in  a  thin  layer — thus  allowing  escape  of  any  small  air  bubbles. 
Now,  I  prefer  a  small  spatula  to  place  the  investment  about  the  wax  inlay,  forcing  a 
little  investment  ahead  of  the  spatula  and  thus  driving  the  air  ahead  and  out  of  the 
corners  and  depressions  in  the  wax.  I  build  up  investment  about  the  wax  until  it 
is  a  thickness  of  probably  a  quarter  of  an  inch  all  around.  Now  I  place  investment 
over  all  the  inside  wall  of  the  flask  and  set  by  a  twisting  or  rotating  movement  onto 
the  crucible  former  and  carefully  proceed  to  fill  it  full  with  remainder  of  investment, 
not  jarring  it,  as  I  wish  not  to  liberate  any  of  the  amount  of  air  still  contained  in  the 
investment  and  by  so  jarring  it  would  gather  together  this  air  and  is  very  liable  to 
collect  on  the  wax  model  in  little  air  bubbles,  which,  when  your  cast  comes  forth, 
you  discover  as  little  fine  nodules  of  gold,  which  you  wish  were  not  there  as  it  inter- 
feres with  its  being  a  perfect  reproduction  of  your  wax. 

Now  give  the  investment  from  fifteen  to  thirty  minutes  to  set  before  applying 
slow  heat  to  dry  it  out.  When  all  moisture  is  gone  and  the  wax  has  been  absorbed 
and  vaporized,  place  in  machine,  melt  pellet  of  gold  and  cast.  I  aim  to  have  the 
pellet  of  gold  about  three  times  the  bulk  of  the  inlay.  The  heat  for  melting  the  gold 
should  be  very  intense  and  concentrated  as  with  the  nitrous  oxide  flame  or  the  electric 
arc,  as  the  gold  should  be  in  as  fluid  a  state  as  mercury. 

CASTING 

The  casting  may  be  done  by  any  of  the  machines  now  on  the  market,  pnn-iding 
\ou  can  get  absolute  accurac}'. 

In  experimenting  with  the  different  grades  of  gold  to  obser\'c  the  contraction, 
1  can  but  recommend  that  when  you  desire  absolutel>-  the  best  results,  you  must  use 
pure  gold.  Dr.  Price,  of  Cleveland,  has  done  some  very  fine  research  work  along 
this  line,  demonstrating  both  expansion  and  contraction  of  gold  and  its  alloys,  also 
expansion  and  contraction  of  our  present  investment  materials,  which  you  will  find 
in  the  May,  1908,  number  of  the  Items  of  Interest.  You  may  cast  your  inlay  with  the 
lower  K.  golds  and  get  a  result  which  to  the  operator  who  is  not  scrupulously  observ- 
ing might  seem  to  be  good,  but  when  you  examine  for  an  absolutely  perfect  adaptation 
you  find  it  deficient  somewhere,  owing  to  the  contraction  of  the  metal. 

The  casting  of  the  hollow  inlay  has  appealed  to  me  because  I  always  looked 
upon  the  hollow  matrix  inlay  with  favor,  and  employed  it  wherever  the  case  per- 
mitted me  to  do  so,  consequently  when  taking  up  the  casting  I  began  trying  different 
ideas  to  obtain  the  hollow  cast  inlay.  The  best  method  I  have  found,  up  to  date,  is 
a  little  copper  bulb  with  a  handle  attached  to  one  side  of  it  and  a  small  point  a  little 
larger  than  a  needle  attached  to  the  other  side,  which  is  wrapped  with  absorbent 


86  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

cotton  or  fibre  asbestos;  then  by  heating  the  bulb  hot,  enough  heat  passes  into  the 
point  so  that  by  touching  the  wax  inlay  where  I  desire  the  hollow  part,  the  point 
will  melt  the  wax  and  the  absorbent  draw  the  melted  wax  away,  leaving  just  as  much 
of  a  hollow  portion  as  you  desire. 

The  hollow  inlay  gives  us  a  larger  layer  of  cement  just  over  the  pulp  and  insulates 
it  from  the  metal  body  and  eliminates  the  thermal  shock,  as  where  we  desire  this 
inlay  we  usually  have  cavities  which  are  in  just  such  a  location  as  to  be  particularly 
sensitive.  They  also  give  us  more  attachment  for  the  cement  which  serves  to  in- 
crease the  value  of  retention. 

CEMENTING   AND   FINISHING 

When  our  inlay  has  been  formed  and  tried  to  the  cavity  and  found  to  be  per- 
fectly satisfactory,  set  it  with  a  very  fine  grained  inlay  cement  and  burnish  all 
borders  and  polish,  and  if  you  are  like  me,  you  will  at  this  time  think  of  our  grand 
old  Professor  Watling,  when  he  said,  in  polishing  the  gold  filling,  give  it  the  polish 
of  the  inside  of  your  watch  case. 

SUMMARY 

In  summing  up,  let  me  say,  first,  make  a  study  of  the  conditions,  with  your 
patient's  benefits  uppermost  in  your  mind;  use  the  cast  inlay  if  in  your  judgment 
the  restoration  will  be  the  very  best  that  can  be  done  by  any  known  method;  if  not, 
then  use  that  which  will  give  such  a  result. 

Do  not  insert  the  inlay  until  you  are  master  of  the  cavity  formation  and  know, 
absolutely  know,  that  the  cavity  formed  will  hold  it.  Know  that  your  wax  inlay 
is  as  near  perfect  as  you  can  mold  it  and  get  an  absolute  duplicate  in  the  gold.  Do 
not  insert  an  imperfect  inlay  because  you  dislike  to  do  it  over  again.  Be  a  man  and 
take  the  bitter  with  the  sweet.  Your  patient  will  appreciate  your  interest  in  having 
your  work  right,  but  will  despise  you  when  she  discovers  you  have  deceived  her  by 
accepting  your  fee  for  a  defective  operation. 

The  measure  of  success  we  are  to  meet  with  lies  in  direct  proportion  to  the  care 
which  we  use  in  the  preparation  of  our  work.  It  is  true  to  the  same  extent  as  with 
any  other  class  of  work;  a  man's  individuality,  his  honesty  of  purpose,  his  character, 
his  appreciative  sense  of  his  position  in  his  chosen  profession  towards  his  services  to 
humanity,  are  all  distinctly  shown. 

If  the  operator  is  not  willing  to  give  time  and  study  and  research  work  in  ex- 
perimenting to  bring  this  method  under  his  control  that  he  may  better  his  services 
to  his  patients,  I  would  advise  him  to  let  it  alone.  If  the  same  operator  is  still 
unwilling  to  better  his  services  to  his  patients  along  even  the  older  methods  at  hand 
and  still  persists  in  staying  in  the  same  old  rut  at  this  day,  it  would  be  just  as  well  for 
his  patients  if  Divine  Providence  should  conclude  that  his  services  were  better  needed 
in  other  fields. 

That  which  I  have  desired  most  to  impress  upon  you  is  thoroughness. 

The  dentist  who  is  of  the  greatest  value  in  his  community  is  the  one  who  is 
ever  alert  to  every  progressive  step  that  will  in  any  way  benefit  his  patient.  Such 
a  man  is  elevating  his  profession,  is  making  the  best  of  the  talents  which  have  been 
given  him,  and  lastly,  doing  the  greatest  amount  of  good  for  himself. 

DISCUSSION 

Dr.  L.  E.  Custkr,  Dayton,  O.:  I  cannot  to  any  extent  disagree  with  any  of  the  points  that  have 
been  brought  out  in  this  most  kindly  and  exxellent  paper  by  Dr.  Lyons,  but  rather  wish  to  confirm 
some  of  the  statements  wliich  he  has  made.     I  wish  at  the  outset  to  pay  a  few  words  of  tribute  to 


THE  CAST  GOLD  I  NLA  Y  87 

Dr.  Taggart.  We  are  prone  to  think  of  the  cast  inlay,  or  the  invention  of  Dr.  Taggart,  as  one  not 
meriting  what  has  already  been  said  of  it,  because  of  its  extreme  simplicity.  When  a  novice  looks  at 
a  complicated  machine,  with  all  the  levers,  springs  and  wheels,  he  stands  back  in  amazement  and  says 
to  himself,  "What  a  genius  that  man  must  have  been  who  invented  that."  However,  when  a  genius 
takes  hold  of  such  an  appliance  as  that  and  has  reduced  the  large  number  of  springs,  levers  and  wheels 
to  a  small  number,  to  perform  the  same  function,  and  has  simplified  an  extremely  complicated 
machine,  to  the  thoughtful  person  that  is  the  machine  in  which  genius  is  displayed.  The  simpler 
machines  are  those  in  which  the  greater  exercise  of  judgment  and  of  patience  has  been  used.  And  so 
I  would  say  of  the  invention  of  Dr.  Taggart,  that  we  are  prone,  I  think,  not  to  give  it  the  full  measure 
of  credit  which  is  due  this  invention,  because  of  its  extreme  simplicity — a  simplicity  which  in  the  year 
and  a  half  since  its  introduction  has  been  the  means  of  placing  upon  the  market  possibly  fifty  different 
methods  of  doing  essentially  the  same  thing;  I  say,  it  is  such  a  simple  thing  at  this  date  that  we  are 
liable  not  to  give  the  full  measure  of  credit  to  the  man  who  worked  out  and  who  simplified  this  process. 

Coming  now  to  the  paper,  in  speaking  of  cavity  preparation,  I  think  that  we  have  had  enough 
experience  with  inlays,  both  porcelain  and  gold,  to  know  that  the  adhesive  property  of  the  cement  is 
not  the  most  effective  thing  in  holding  the  filling  in  the  cavity;  that  in  just  the  proportion  as  we  are  able 
to  so  form  the  cavity  that  the  filling  will  be  held  mechanically,  keeping  in  mind  the  direction  of  stress 
of  mastication,  will  the  filling  be  retained,  and  it  is  a  mistake  on  the  part  of  any  one  beginning  this 
work,  who  has  not  made  inlays  of  either  gold  or  porcelain,  to  trust  much  to  the  retentive  property 
of  the  cement.  We  must,  in  some  manner  or  other,  form  a  dove-tail,  and  that  can  be  done  at  the  same 
time  and  the  filling  can  be  so  shaped  that  it  can  be  introduced  as  one  plug  of  metal  or  porcelain. 

The  essayist  spoke  of  inlays  for  the  anterior  teeth,  and  did  not  place  much  importance  upon  the 
value  of  cast  inlays  in  this  part  of  the  mouth.  I  think  that  here  is  just  as  important  a  place  as  any 
other,  and  especially  on  the  corner  of  an  incisor  where  porcelain,  by  reason  of  its  brittle  characteristics, 
of  which  you  are  all  familiar,  cannot  withstand  the  stress;  here  I  believe  that  the  Taggart  inlay  is  the 
thing,  but  I  would  call  to  your  attention  the  value  of  platinum  combinations  with  gold,  when  the 
filling  is  used  in  this  position.  Platinum  melts  at  about  .3600  Fahrenheit,  and  you  know  that  there 
are  only  two  means  by  which  that  can  be  melted  at  present,  the  oxy-hydrogen  blow-pipe  and  the 
electric  arc.  With  the  oxy-hydrogen  we  have  enough  heat  to  melt  it  in  small  quantities,  but  with  the 
arc  light  we  have  6,000  degrees  of  heat  at  our  command  and  with  this  device  it  is  possible  to  fuse  pure 
platinum  with  proper  investment  material.  We  may  make  a  pure  platinum  filling  in  this  manner; 
however,  it  would  call  more  especially  for  proper  investment  than  for  anything  else,  for  withstanding 
so  high  a  heat  at  the  time  of  casting  it  would  be  better  if  we  were  to^dd  some  gold  to  the  platinum — 
about  three-fourths  of  gold  and  one-fourth  platinum.  It  does  not  materially  affect  the  color.  I 
think  the  color  is  better  than  with  pure  platinum,  so  I  would  suggest  the  use  of  platinum  and  gold  cast 
fillings  for  the  incisors  and  any  conspicuous  fillings  for  the  incisor  corners  and  the  anterior  proximal 
bicuspid. 

The  doctor  suggests  the  warming  of  the  inlay  and  the  wax  impression  material  in  water.  I  have 
felt  from  the  first  that  the  forming  of  it  on  a  stick  with  a  little  sharpened  point,  and  that  heated  over 
a  flame  to  bring  it  to  the  right  degree  of  softness,  will  give  you  a  better  impression  of  the  cavity,  because 
of  the  fact  that  the  surface  is  quite  soft  and  it  is  forced  in  every  detail  and  line  of  the  cavity  on  the  in- 
side by  the  harder  material  back  of  that.  I  rather  lean  towards  that  method  of  obtaining  the  impres- 
sion of  the  cavity. 

The  doctor  pays  much  attention  to  the  wax  filling.  I  think  that  this  is  just  the  thing  to  do.  be- 
cause at  this  stage,  a  few  moments  spent  in  the  proper  shaping  and  dressing  of  the  wax  fillings  is  time 
well  spent  and  will  save  you  much  more  time  when  it  comes  to  the  setting  of  the  filling.  I  prefer  to 
do  this  also  for  another  reason,  and  that  is  that  it  is  easier  at  the  time  of  setting  to  burnish  and  thin 
the  edge  in  closer  apposition  to  the  margin  than  it  is  in  the  unfinished  or  heavy  margin  of  your  filling. 
You  have  thus  two  advantages  of  dressing  the  wa.x  beforehand,  or  if  you  fail  to  do  that,  trace  your 
filling  and  get  a  close  fit  with  the  margin  before  setting. 

In  removing  the  wax  filling  I  have  always  liked  to  warm  the  end  of  the  sprue  wire  and  imbedding 
that  in  the  inlay  it  serves  as  a  handle  by  which  the  filling  can  be  easily  removed.  At  the  time  of  taking 
the  wax  out  of  the  cavity  you  can  feel  whether  or  not  you  have  prepared  your  cavity  so  that  it  can  be 
properly  drawn  out,  and  if  you  have  in  any  place  a  slight  undercut,  of  course  the  enlarged  part  can 
be  readily  rubbed  down  so  that  it  can  be  lifted  from  the  cavity  to  be  .set  again,  then  going  over  the  mar- 
gins for  the  last  time.  I  have  always  been  better  satisfied  with  the  melting  in  of  the  sprue  wire  than 
drawing  or  lifting  the  filling  out  of  the  cavitj'  by  the  other  method. 

I  think  in  our  gold  fillings  we  should  use  pure  gold,  because  of  the  fact  that  it  can  be  easily  and 
readily  burnished  to  fit  the  cavity  margins.     Never  use  a  lower  karat. 

In  addition  to  the  notes  which  I  have  taken  on  the  paper  I  would  like  to  make  a  few  suggestions 
which  have  come  about  through  my  own  experience.     Once  in  a  great  while  an  inlay  will  be  made 


88  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

that  has  not  been  sharply  cast;  it  fits  the  cavity  to  the  very  corners  but  its  margins  are  rounded  instead 
of  sharp.  This  being  the  case,  it  is  an  easy  matter,  if  the  margins  are  excessive,  to  set  that  filling  and 
immediately  afterwards  go  over  the  margins,  turning  an  old  carborundum  wheel  which  has  been  filled 
with  the  grindings  of  gold,  revolving  that  towards  the  margin,  and  you  can  push  up  the  pure  gold  or 
flow  it  ahead  of  the  wheel  until  you  have  a  perfect  adaptation.  This  can  be  done  where  the  corners 
have  not  been  filled  out  entirely.  There  are  many  faulty  margins  that  can  be  made  absolutely  good 
in  that  way.  If  the  filling  is  dry  and  the  carborundum  wheel  is  dry  it  is  wonderful  to  what  extent  you 
can  push  the  gold  towards  the  margin  by  reason  of  the  wonderful  cohesiveness  characteristic  of  pure 
gold. 

Another  point  is  this.  In  the  proximal  fillings  there  will  always  be  noticed  a  point  of  contact 
with  the  neighboring  teeth  which  is  a  little  flat  place  right  at  that  point.  You  can  take  a  bit  of  22 
karat  gold,  about  the  size  of  a  pin  head,  melt  it  on  there,  round  it  out,  and  it  gives  a  rounded  contact 
surface,  to  one  which  is  usually  either  flat  or  concave.  Sometimes  these  fillings  are  so  well  and  closely 
adapted  to  the  cavity  that  in  a  quite  frail  tooth  you  may  chip  off  a  little  margin  of  the  enamel.  You 
need  not  make  a  new  fiUing  in  this  case.  Heat  the  filling  to  redness  under  the  blow-pipe  and  let 
cool  without  water,  and  place  in  the  cavity  a  little  bit  of  platinum  and  gold  foil,  or  inlay  platinum 
matrix  material  should  be  placed  over  the  break.  When  the  foil  has  been  annealed  it  will  cohere  to 
the  gold  filling,  and  it  can  be  formed  in  a  moment  to  the  enamel  margin,  and  the  filling  may  be  removed 
and  this  little  cup-shaped  cavity  can  then  be  filled  full  of  22  gauge  gold,  and  your  filling  will  be  as 
good  as  ever. 

Dr.  IVIuiR,  Detroit,  Mich.:  I  want  to  congratulate  Dr.  Lyons  upon  his  paper  this  evening. 
When  I  first  started  making  gold  inlays,  I  had  lots  of  failures,  and  was  just  about  totally  disgusted 
with  gold  inlays,  but  now  I  have  very  good  success.  The  dentists  who  use  gold  foil,  and  have  always 
used  it,  cannot  be  blamed  for  not  wanting  to  take  to  the  gold  inlay,  but  there  are  comparatively  very 
few  good  gold  fillings  inserted.  There  is  so  much  in  favor  of  the  gold  inlay  that  I  think  every  man  should 
have  an  adequate  inlay  machine  for  making  them.  They  must  be  used  with  discretion,  of  course. 
Those  enthusiasts  who  have  used  porcelain  indiscriminately,  have  some  regrets,  but  it  does  not  follow 
that  everybody  is  going  to  take  up  the  gold  inlay  and  use  it  where  it  should  not  be  used. 

Dr.  Taggart's  paper,  I  think  it  was  in  the  December  issue  of  the  Denial  Register,  gives  a  very 
concise  and  accurate  method  of  each  step  of  making  the  wax  model.  I  got  more  from  that  than  from 
anything  that  I  ever  read  on  the, subject.  The  cavity  must  be  prepared  properly,  and  I  like  to  heat 
the  wax  in  water.  Dry  heat  is  all  right  if  you  do  it  properly,  if  you  get  it  just  exactly  right,  it  will 
be  all  right,  but  it  is  easier  to  get  it  exactly  right  in  water,  and  the  water,  of  course,  must  be  of  the  right 
temperature.  After  pressing  wax  into  the  cavity  have  the  patient  bite  and  cool  it  with  a  stream  of 
cold  water.  Trim  it  off,  and  then  smooth  it  with  Three-in-One  oil.  There  is  something  in  that  oil 
that  dissolves  the  surface  of  the  wax  and  gives  you  a  perfectly  smooth  surface.  In  approximal  cavities, 
use  tape;  put  some  Three-in-One  oil  on  it,  and  run  it  in  between  the  teeth,  and  it  will  give  you  a  per- 
fectly smooth  surface  there.  Remove  the  inlay  by  the  use  of  a  fine  copper  sprue  wire;  heat  it  over  the 
alcohol  lamp,  or  gas;  insert  it  into  the  filling  with  the  right  hand,  holding  in  the  left  hand  the  water 
syringe  filled  with  cold  water,  and  when  the  sprue  wire  goes  into  the  inlay,  put  stream  of  cold  water 
on  it.  Remove  the  inlay  by  grasping  wire  with  pliers.  If  it  comes  out  hard,  put  it  back  again.  If 
there  is  a  slight  undercut,  it  will  burnish  down.  Before  you  take  it  out  the  last  time,  see  that  the 
margins  are  all  right.  After  it  is  out,  add  a  small  drop  of  wax  from  spatula  for  contact  point.  Now 
take  care  in  mixing  your  investment  compound.  Do  not  attempt  to  make  gold  inlays  with  a  poor 
machine  and  with  a  poor  investing  compound.  You  must  have  good  material  to  get  good  results.  Care- 
fully mix  your  investment  compound.  I  mix  it  in  a  saucer.  Don't  get  it  too  thick;  spread  it  thoroughly 
over  the  saucer  making  a  thin  layer,  and  shake  it  well  and  blow  onit,  making  the  bubbles  disappear  that 
rise  to  the  surface.  They  can  be  avoided  by  carefully  mixing  investment  compound  and  applying  same 
to  the  inlay  with  a  camel's  hair  brush.  After  you  have  your  inlay  invested,  take  care  of  that.  I  learned 
this  afternoon  that  men  have  had  a  lot  of  failures  due  to  careless  drying  out  You  cannot  hurry  your 
investment  in  drying.  I  set  it  aside  for  an  hour  after  mixing,  and  let  it  thoroughly  harden.  Then 
put  it  on  a  slow  Bunsen  burner  or  in  an  oven,  something  of  uniform,  steady  heat,  and  gradually  increase 
that  heat,  and  I  like  to  leave  it  there  an  hour  until  the  moisture  is  well  out  of  the  investment  compound, 
and  there  is  no  steam  coming  from  it.  Then  you  can  give  it  as  much  heat  as  you  like.  If  you  attempt 
to  melt  your  wax  before  the  moisture  is  out  of  the  plaster,  the  wax  will  bubble  out  of  the  cavity,  and 
then  you  have  a  rough  sediment  on  the  inside  of  your  cavity,  and  this  spoils  the  inlay.  In  heating 
your  investment,  don't  get  your  investment  too  hot.  It  is  not  necessary  to  get  it  hot  enough  to  melt 
your  cup;  just  get  it  hot  enough  to  melt  the  wax.  It  will  smoke  a  little  while  and  your  investment 
will  be  black.     Apply  blow-pipe  until  the  bluish  colored  flame  has  entirely  disappeared,  and  possibly 


THE  CAST  GOLD  I  NLA  Y  89 

a  little  longer.  It  is  only  necessary  to  burn  out  all  the  wax,  and  further  heating  does  not  do  the  invest- 
ment any  good.  You  cannot  get  satisfactory  results  for  an  inlay  with  any  other  gold  but  pure  gold. 
22  karat  will  not  do.  I  like  to  try  the  inlay  in,  as  soon  as  I  have  it  cast,  and  cut  the  sprue  otf.  If  it 
goes  to  its  place  nicely,  take  it  out  and  polish  it  with  sand  paper  disc,  and  with  the  grinding  surface  of 
a  molar,  you  will  have  to  cut  down  in  there  probably  with  a  fine  bur — a  very  small  plug  finishing  bur 
or  a  No.  !^  or  a  No.  1  bur  for  the  fissures.  A  dull  one  does  the  work  very  nicely;  and  then  burnish. 
Put  the  inlay  in  the  cavity,  and  before  setting,  thoroughly  burnish  it  around  the  margin.  I  do  not  like 
to  burnish  after  setting.  You  must  burnish  before  the  cement  thoroughly  sets.  Unless  it  fits  into  a 
wedge-shaped  cavity  very  tightly,  you  are  liable  to  move  it,  and  if  you  burnish  it  before  cementing, 
you  do  not  have  very  much,  if  any,  burnishing  to  do  after.  Polish  it  with  sand  paper  discs,  or  fine 
stones  rotated  on  the  margins  from  the  inlay  towards  the  tooth.     Finish  with  pumice. 

Dr.  W.  L.  Williams,  Sault  Ste.  Marie:  I  have  had  very  little  experience  in  cast  gold  inlays,  and 
I  am  here  to  learn,  and  I  think  we  ought  all  to  honor  the  pioneers  of  this  work.  It  is  those  men  whose 
names  will  go  down  in  history,  and  as  I  am  not  a  pioneer.  I  honor  the  gentleman  who  read  the  paper, 
and  my  friend,  Dr.  Custer,  and  will  beg  to  be  excused  from  saying  anything  more. 

Dr.  Travis,  Plymouth:  The  paper  has  been  so  ably  written  and  so  well  discussed  up  to  the 
present  time  that  while  there  may  be  a  great  deal  that  could  be  said  upon  this  subject,  yet,  it  seems 
to  me,  that  there  is  very  little  that  we  could  say  tonight  that  would  add  very  much  to  what  has  already 
been  said.  However,  we  all  know  that  the  gold  inlay  of  the  cast  variety  has  been  a  blessing  to  the 
profession  and  to  our  patients,  and  that  it  will  be  received  by  both  alike  as  a  blessing.  We  know,  too, 
that  it  possesses  qualities  that  no  other  filling  possesses.  We  obtain  by  this  method  a  strengthening 
of  the  walls,  and  a  more  perfect  sealing  of  the  cavity,  and  at  the  same  time  we  obtain  a  non-conductor. 
There  are  a  great  many  cavities  that  we  have  to  deal  with  where  it  would  not  be  wise  for  us  to  use  the 
gold  inlay;  however,  up  to  the  present  time  there  seems  to  be  nothing  equal  to  it  in  other  cavities,  and 
it  seems  that  a  great  many  of  us  are  led  at  this  time  to  use  the  gold  inlay  in  cases  where  it  is  not  in- 
dicated. C.  N.  Johnson,  who  has  been  one  of  the  greatest  advocates  of  the  gold  foil  filling,  is  now  one 
of  the  strongest  advocates  of  the  gold  inlay,  and  yet  he  has  said  that  if  the  inlay  had  been  used  for 
forty  years  or  more  as  the  foil  filling  has  been,  and  we  were  now  to  introduce  the  foil  filling,  that  we 
would  be  just  as  likely  to  go  into  ecstasy  over  the  use  of  the  foil  filling  as  we  are  now  over  the  inlay. 
The  methods  of  producing  this  inlay  by  various  instruments  is  something  that  1  am  not  very  familiar 
with,  but  in  the  clinics  that  I  have  witnessed  it  appears  to  me  that  a  great  many,  in  demonstrating  this, 
have  been  satisfied  by  submitting  to  us  samples  that  are  a  long  ways  from  perfect,  and  they  always  do 
that  with  the  apology  that  this  is  merely  a  clinic  and  that  it  has  been  done  hastily;  that  it  approxi- 
mately fills  the  cavity,  and  that  you  see  the  principle,  and  now  if  you  will  only  give  it  time  that  you 
can  produce  perfect  results  and  get  perfect  borders;  but  only  in  very  few  cases  we  find  that  they  can 
with  uniformity  get  these  perfect  borders.  I  believe,  as  a  member  of  the  profession — and  most  of  us 
believe  the  same  way — that  it  is  not  the  price  of  the  instrument  with  which  we  are  to  attain  these 
results  that  determines  our  choice,  but  rather  that  we  may  be  positive  that  with  this  instrument  we 
shall  be  able,  uniformly,  to  secure  perfect  borders.  What  I  mean  by  perfect  borders  would  be  a  border 
sufficiently  perfect  that  we  could  burnish  over  and  get  a  perfectly  tight  border,  and  protect  the  cement 
so  that  none  could  tell  it  from  the  gold  foil  filling. 

Dr.  J.  W.  Lyons:  The  discussion  of  the  paper  has  not  been  agreeable  to  me  in  a  way  I  would 
like  to  have  it.  In  preparing  this  paper  I  hoped  to  get  a  great  many  pointers  myself  in  the  discussion 
of  it,  from  other  men,  because  I  feel  that  there  are  many  things  yet  to  be  learned  about  the  cast  inlay; 
it  is  not  nearly  perfect,  by  any  means,  and  there  are  a  great  many  things  to  be  developed  yet. 

Dr.  Custer  thought  I  did  not  lay  stress  enough  upon  the  use  of  the  cast  inlay  in  the  anterior  teeth. 
I  do  not  like  to  use  the  gold  if  we  can  get  away  from  it  wherever  it  is  possible  to  use  porcelain,  and 
I  think  it  is  possible  by  proper  methods.  I  like  to  see  the  porcelain  inlay  used  in  the  anterior  teeth, 
but  where  great  stress  is  brought  to  bear  upon  it,  and  where  it  is  impossible  to  hold  it,  then  I  would 
resort  to  the  gold  inlay,  because,  without  regard  to  my  own  feelings  as  to  ideal  methods,  in  my  own 
mind  I  feel  that  the  patient's  benefits  are  the  first  thing  to  be  considered.  Durability  has  much  to 
do  with  the  building  up  of  a  practice  and  the  building  up  of  your  reputation.  If  you  insert  fillings 
or  inlays  and  they  have  to  be  restored  in  a  very  short  time,  you  lose  the  respect  of  your  patient;  you 
cannot  hope  to  hold  the  respect  of  your  patients  in  having  work  fail;  although  you  may  desire  to  have 
a  porcelain  stay  in  place,  thinking  that  it  is  much  more  esthetic  than  the  unsightly  gold,  yet  your 
patient  will  think  more  of  you  if  your  work  stands. 

I  thank  Dr.  Custer  very  much  for  the  added  suggestions  that  he  has  given  us,  and  the  gentleman 
here  on  my  right,  because  I  know  from  his  talk  that  he  has  been  up  against  a  great  many  of  the  same 
things  that  I  have  been. 


90 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


A  SOLDERING  DEVICE 

By  Dr.  T.   B.   MaGill,   Kansas  City,  Mo. 

Screw  the  flexible  arm  on  to  the  crown  foot,  then  screw  on  the  clamp-pliers; 
open  pliers  and  insert  the  iron  spoon  (one  or  more).  The  pin  in  the  pliers  to  go 
through  the  holes  in  the  spoons. 

Now  any  soldering  which  has  to  be  invested  can  be  invested  in  the  bowl  of  the 
spoon.  (Crown  or  Bridge.)  Coarse  investment  is  better  as  it  is  not  so  apt  to  blow 
up  by  heating  too  rapidly. 


A  soldering  device,  bv  T.  B.  MaGill 


After  case  is  invested  the  flexible  arm  can  be  adjusted  high  above  a  Bunsen 
flame  and  as  it  heats  up  bend  down  into  flame.  Use  a  very  small  amount  of  invest- 
ment, a  film  1-16  in.  thick  is  plenty,  the  spoon  holds  it  in  shape,  also  distributes  heat 
evenly. 

To  solder,  place  an  empty  spoon  in  pliers  with  one  holding  invested  case.  Place 
the  solder  in  empty  spoon.  Another  spoon  may  be  adjusted  for  another  karat 
solder  or  flux.  Apply  heat  from  beneath  until  case  is  cherry  red,  then  apply  solder 
and  flame.  By  using  flexible  arm  you  can  get  to  any  part  of  investment  with 
blow-pipe. 


CASTING:  A  RETROSPECT 

By  Dr.  J.  G.   Lane,   Philadelphia 

When  it  first  became  known  that  certain  areas  in  Alaska  wcie  rich  in  gold, 
ravenous  prospectors  and  claim-stakers  jostled  with  and  fought  each  other  in  their 
mad  rush  over  the  coveted  territory.  This  proceeding  was  carried  on  amid  such  a 
degree  of  excitement, — each  person  fearing  that  each  and  every  other  person  might 
find  something  better  than  he  himself — that  the  entire  field  was  sort  of  wallowed 
over,  and  worked  coo  superficially  to  find  out  what  conditions  really  did  exist.  After 
the  place  was  thus  imperfectly  worked  out  in  the  first  spasm  of  excitement,  the  same 
ground  was  again  covered  in  a  manner  that  was  sane  and  sensible  enough  to  unearth 
the  real  value  of  the  environment.  These  same  conditions  obtain  in  our  profession 
as  often  as  new  or  novel  procedures  and  methods  are  sprung  upon  us.  And  the  more 
unique  and  novel  the  innovation,  the  more  this  condition  obtains.  In  this  particular, 
casting  has  been  an  exception  only  in  that  it  has  been  the  most  extreme  case  of  this 
kind  that  has  ever  come  within  our  observation.  And  now  that  the  first  grand  rush 
for  supremacy  and  record  is  on  the  wane,  it  is  high  time  that  we  begin  to  look  back 
over  the  field,  take  a  retrospect  view  of  what  has  been  done,  the  theories  and  methods 
advanced,  and  to  sift  the  real  wheat  from  the  chaff.  This  sifting  and  winnowing  is 
likely  to  send  many  pet  theories  and  ideas  to  the  wind — never  to  return;  and  indeed 
wisely  so.  The  dental  journals, — aye,  and  even  textbooks  on  the  subject  in  question, 
— tell  us  all  manner  of  theory  and  methods  in  the  art;  many  of  these  are  so  un- 
reasonable, fallacious  and  unscientific  in  their  very  aspect,  that  we  cannot  but  assume 
that  the  exponent  of  such  has  in  all  probability  arrived  at  his  conclusion  theoretically, 
rather  than  scientifically  or  clinically.  While  we  know  that  the  profession  as  a  whole 
has  been  wondrously  benefited  by  the  result  of  all  this  effort,  yet  we  cannot  believe 
other  than  that  many  things  which  have  been  written  and  said  on  this  subject  from 
time  to  time,  have  proved  to  be  an  injury  to  the  cause  rather  than  a  help. 

Quoting  Dr.  C.  S.  Van  Horn,  Dental  Cosmos,  Vol.  LI,  p.  549: — "At  present  our 
work  in  this  field  is  largely  empirical;  we  have  not  practised  casting  sufficiently  long 
to  have  established  it  on  a  scientific  basis;  consequently  we  are  too  many  times 
between  the  devil  and  the  azure  brine  to  know  the  how  and  the  why.  Some  day 
the  clouds  will  roll  away."  And  in  accordance  with  this  thought,  we  think  it  high 
time  that  some  of  the  overhanging  clouds  should  roll. 

The  purpose  of  this  paper,  therefore,  will  be  to  point  out  some  of  the 
extremely  opposite  views  that  have  been  taken  by  various  experimenters,  who, 
by  experiments  conducted  technically,  theoretically,  scientifically,  and  clinically, 
have  endeavored  to  reduce  the  art  of  casting  to  a  true  and  proper  basis. 

Let  us  consider  the  impression  method  for  inlay  work  as  advocated  by  Dr. 
Weston  A.  Price,  Items  of  Interest,  Vol.  XXX,  p,  3G3  and  938,  and  by  various  other  inlay 
workers.  This  method  has  adherents  both  in  the  clinic  and  in  literature;  the  usual 
arguments  advanced  in  its  favor  being  the  lessened  possibility  of  distortion  of  an 
impression  as  compared  to  a  possibility  of  the  same  in  a  finished  pattern 
while  being  removed  from  the  teeth  or  cavit\';  time  saved  at  the  chair  and 
less    annoyance    to    the    patient.       Let    us    quote    your    essayist    from    the    Dental 


92  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Dzge^/,  Vol. XV, p.436 — "The  pattern  for  a  gold  inlay  should  be  made  in  the  cavity 
that  is  to  receive  the  finished  casting.  This  insures  a  better  adaptation  than 
can  be  had  by  any  method  thus  far  devised  for  making  the  pattern  in  a  model. 
In  the  former  method  we  have  three  transfers — cavity  to  pattern,  pattern  to  in- 
vestment, and  investment  to  gold.  In  the  latter  we  have  five  transfers — cavity 
to  impression,  impression  to  model,  model  to  pattern,  pattern  to  investment,  and 
investment  to  gold;  or,  if  the  casting  is  done  directly  in  the  model  we  still  have 
four  transfers  by  the  latter  method.  In  any  transfer  we  can  scarcely'  avoid  losing 
detail  and  definition;  therefore,  the  fewer  the  transfers  the  better  the  inlay  is 
going  to  fit, — all  other  things  being  equal.  Furthermore,  there  is  vastly  more  pos- 
sibility of  distortion  in  an  impression  than  in  a  pattern.  This  can  easilj'  be  under- 
stood when  we  consider  that  the  pattern  is  adapted  to  the  interior  of  the  cavity  only; 
while  an  impression  for  a  model  is  adapted  not  only  to  the  interior  of  the  cavity  but 
also  to  the  exterior  of  the  tooth — as  well  as  to  adjoining  teeth.  Removal  of  such  an 
impression  from  the  tooth  or  teeth  is  almost  sure  to  distort  it;  nor  is  there  by  this 
method  any  possibility  of  determining  whether  distortion  is  present  or  not  until  the 
inlay  is  made,  i^y  the  direct  method  there  is  very  little  possibility  of  distortion; 
or  if  there  is  a  suspicion  that  distortion  is  present,  it  can  easily  be  proven  and  corrected 
before  proceeding  further."  Instead  of  the  impression  method  amounting  to  a  saving 
of  time  in  the  chair,  we  believe  it  to  take  more  time  than  the  pattern  method,  because 
of  the  fact  that  two  operations — one  for  impression  and  another  for  bite — are 
necessary.  And  if,  therefore,  as  much  time  is  consumed,  the  patient  has  not  re- 
ceived the  benefit  of  any  spared  annoyance.  If,  as  is  advocated  by  some,  the 
model  for  such  a  case  is  to  be  made  of  amalgam,  and  the  wax  pattern  for  the  inlay 
then  made  in  the  amalgam  model,  we  at  once  find  that  the  time  consumed  after  the 
impression  and  bite  have  been  taken,  is  very  prohibitory — in  addition  to  the  almost 
certain  result  of  inaccuracy  on  account  of  too  many  transfers,  and  the  possibility  of 
distortion.  It  is,  therefore,  patent  to  all  that  the  method  which  will  insure  the 
greatest  accuracy  of  adaptation  is  the  one  which  is  most  desirable  to  follow. 

We  believe  that  the  more  general  use  of  inlays  has  done  much  toward  educating 
the  profession  in  general  to  appreciate  a  higher  standard  of  cavity  preparation. 
As  to  fundamental  conditions  which  should  obtain  in  this  part  of  the  work,  all  seem 
to  be  pretty  nearly  a  unit.  In  detail,  however,  there  are  wide  differences.  Let  us 
quote  Dr.  P.  B.  McCoullough,  Dental  Cosmos,  Vol.  LI,  p.  1175: — "No  filling  material 
has  at  its  square  edge  the  strength  of  the  square  edge  of  enamel.  The  beveling  of 
enamel  margins  for  protection  is  illogical  when  the  weaker  body  is  to  provide  the 
protection."  Let  us  also  quote  Dr.  Theodore  C.  Trigger,  "Notes  and  Methods  of 
Filling  Teeth  with  Gold  Inlays,"  p.  46 — "The  marginal  edges  of  the  cavity  should  be 
cut  straight  and  beveling  avoided."  The  authority  quoted  repeats  this  statement 
on  p.  59  of  the  same  publication.  Let  us  also  quote  your  essayist,  Dental  Cosmos, 
Vol.  LI,  p.  434 — "The  margin  of  a  gold  inlay  being  thoroughly  homogeneous  is 
reliable  even  at  an  angle  of  65  degrees.  This  secures  for  the  enamel  margin  the 
remarkably  strong  angle  of  115  degrees."  This  seems  to  be  just  about  the  extreme 
opposite.  However,  we  feel  positive  that  we  have  seen  our  contention  in  this  upheld 
clinically  at  all  times;  and  we  believe  that  proper  clinical  results  are  most  important. 
For  inlay  work  we  disapprove  of  the  extremely  angular  form  of  cavity  preparation 
generally  known  as  the  "Black  Method,"  and  by  some  inlay  workers  followed  out  in 
cavity  preparation  for  inlays.  We  believe  that  the  inverted  cone  and  square  end 
fissure  burs  have  no  place  in  the  equipment  for  inlay  cavity  preparation.     Quoting 


CASTING:  A   RETROSPECT  93 

again  from  your  essayist,  Dental  Cosmos,  Vol.  LI,  p.  433: — "Sharp  angles  at  the 
cervico-buccal  and  lingual  aspects  of  an  approximo-occlusal  cavity  have  no  point  of 
merit  whatever,  and  serve  only  to  weaken  the  tooth  as  a  whole."  Also  quoting  Dr. 
Trigger  from  the  publication  mentioned  above,  p.  59: — "The  enamel  walls  should 
not  terminate  too  abruptly  in  short  curvatures."  P.  60: — "No  definite  angles  are 
used  in  the  preparation  of  cavities  for  inlays."  And  further  down  the  page,  "At  the 
junction  of  the  gingivo-labial  and  buccal  surfaces  the  cavity  should  be  cut  in  a  rounded 
form."  Dr.  Trigger  then  goes  on  to  state  the  advisability,  and  almost  necessity, 
of  sharp  angular  forms  in  these  parts  of  cavity  preparation  for  gold  foil  fillings. 

Sharp  angles  at  the  points  mentioned  in  the  quotation  of  your  essayist,  have 
the  effect  of  confining  the  area  of  possible  fracture  to  one  point,  while  if  these  parts 
of  the  cavity  have  a  very  slightly  rounding  effect  the  area  of  possible  fracture  is 
distributed  over  the  area  thus  filled  in,  and  no  one  point  will  have  to  endure  the 
encire  violence,  e.  g.,  a  steel  bar  3  inches  in  diameter,  having  a  point  at  its 
center  cut  down  by  a  narrow  sharp  edged  groove  to  1  inch  diameter  will 
fracture  more  readily  under  load  than  if  the  entire  bar  (or  even  a  longer 
distance  in  its  center)  were  only  1  inch  diameter.  If  there  are  sharp  angles  pointing 
outward  from  the  interior  of  a  cavity  there  will  be  similar  angles  in  a  casting  mould; 
these  are  likely  to  receive  slight  abrasion  and  injury  when  the  gold  is  cast  past  and 
against  them,  thus  causing  a  misfit.  The  more  angular  the  cavity  the  more  diffi- 
culty is  experienced  in  getting  the  inlay  properly  seated;  the  surplus  cement  must  fol- 
low a  more  tortuous  line  to  escape.  We  cannot  see  that  sharp  internal  angles  add 
in  any  way  whatever  to  the  degree  of  stability  or  fixation  of  an  inlaj-  after  it  is  cement- 
ed in  position;  nor  can  we  see  how  such  could  in  any  possible  manner  strengthen  the 
operation  and  tooth  as  a  whole.  Furthermore,  there  is  a  possible  element  of  inac- 
curacy of  adaptation  to  sharp  angles  in  making  the  wax  pattern. 

Much  diversity  of  opinion  exists  in  regard  to  the  temperature  the  mould  should 
have  at  the  moment  of  casting.  Quoting  Dr.  Marcus  L.  Ward,  Dental  Cosmos,  Vol. 
LI,  p.  1055: — "We  are  to  cast  our  gold  into  moulds  w^hich  have  been  heated  suffi- 
ciently to  eliminate  all  mechanical  moisture  and  allowed  to  cool  down  tilltheycanjust 
be  handled  with  the  hands  without  discomfort  if  we  are  to  place  the  casting  of  gold 
on  a  practical  as  well  as  scientific  basis*."  Quoting  also  Dr.  C.  R.  Baker,  Dental 
Review,  Vol.  XXIV,  p.  133 — "My  first  conclusion  is, — that  the  only  way  to  cast 
inlays  is  in  a  cold  mould.  .  .  .  With  a  cold  mould  we  get  a  better  specific  gravity." 
Quoting  also  your  essayist.  Dental  Digest,  Vol. XV,  p. 499 — "If  the  flask  contains  a 
mould  of  an  inlay  for  a  double  compound  cavity,  or  one  that  encircles  or  sits  astride 
some  portion  of  the  tooth,  it  should  be  exceedingly  hot  at  the  moment  of  casting. 
This  will  give  the  minimum  of  shrinkage  with  a  given  investment."  And  on  the 
following  page — "For  inlays  representing  simple  interiors,  the  flask  need  not  be 
so  hot  as  for  the  classes  just  described;  but  it  must  always  be  borne  in  mind  that  the 
lower  the  temperature  of  the  flask  the  greater  the  shrinkage,  and  that  the  approxi- 
mate amount  of  shrinkage  desired  shall  determine  the  reduction  of  temperature  in 
the  flask  at  the  time  of  casting." 

Dr.  Ward,  in  the  publication  quoted,  does  not  seem  to  give  any  very  definite 
reason  for  his  belief  regarding  the  temperature  of  the  mould.  Dr.  Baker  states  his 
reason  as  being  that  a  better  specific  gravity  is  obtained.  We  cannot  see  that  Dr. 
Baker's  figures  for  shrinkage  (or  expansion)  in  the  publication  quoted  (pp.  130  and 

*We  are  not  informed  as  to  just  what  this  scientific  basis  is. 


94  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

131),  mean  very  much  unless  the  size  of  the  pattern  for  each  was  given.  On  the 
following  page  we  may  read: — "The  average  size  of  the  wax  cubes  is  .1995  in." 
Unless  the  patterns  had  an  absolutely  uniform  and  stated  size  the  table  would  not 
show  much,  except  hy  computation  if  the  size  of  the  pattern  for  each  experiment 
was  given.  The  sizes  are  not  given  except  as  above.  Experiment  No.  3,  Table  III, 
reads: — "5  dwt.  hot  .2000,  18.308  Pecks,"  and  conveys  to  us  the  information  that 
5  dwt.  of  pure  gold  was  cast  into  a  hot  mould  of  Peck's  investment,  and  that  the 
resultant  casting  measured  .2000  in.  and  had  a  specific  gravity  of  18.308.  No  figures 
are  given  for  the  size  of  the  pattern  for  this  particular  casting.  But  if  the  flasked 
pattern  was  .1995  in.  we  believe  that  the  result  as  stated  is  a  physical  impossibility 
so  far  as  it  pertains  to  the  size  of  the  casting.  Experiments  that  we  conducted  along 
this  same  line  to  determine  figures  on  shrinkage  showed  Peck's  investment  to  have  a 
very  decided  degree  of  contraction  on  being  heated  to  a  high  temperature.  Our 
figures  for  the  particular  experiment  that  might  be  placed  in  comparison  with  the 
above  are  these: — size  of  pattern  .5000  in.  (half  an  inch);  temperature  of  mould, — 
red  heat;  size  of  casting, — .4957  in.;  investment.  Peck's.  This  shows  a  loss  of  .0043 
in.  in  a  casting  made  in  a  mould  as  hoc  as  the  fusing  point  of  the  brass  flask  that  con- 
tained the  mould  would  safely  allow.  In  eleven  of  the  twenty-eight  experiments 
of  Dr.  Baker  we  are  given  figures  which  show  castings  larger  than  the  pattern  (.1995 
in.)  anywhere  up  to  .2030  in. — or  in  one  instance  an  increase  of  .0035  in.,  and  this 
in  a  vacuum  machine.  Two  of  the  tables  given  are  the  data  for  vacuum  machines. 
The  make  of  vacuum  machine  is  not  given,  but  we  assume  that  it  has  iron  flasks. 
Iron  has  an  expansion  equal  to  about  one-half  the  expansion  of  gold;  and  in  order 
to  expand  enough  to  give  a  casting  the  size  of  a  given  flasked  pattern  would  have  to 
be  heated  to  double  the  fusing  temperature  of  gold.  Of  course,  the  investment  would 
not  stand  this;  and  granting  that  it  did,  the  casting  would  show  a  register  only  after 
the  whole  had  cooled  down  to  201 B  degrees — which  register  would  be  only  half  enough 
to  neutralize  the  contraction  of  the  gold.  In  our  experiments  the  best  result  ob- 
tained in  an  iron  flask,  cast  at  red  heat,  gave  a  casting  .4943  in.  from  a  pattern  of 
.5000  in.  Two  other  machines  mentioned  in  the  tables  are  Taggarts  and  Jamesons. 
These  both  have  brass  flasks.  Brass  expands  a  trifle  more  than  gold  at  a  given  tem- 
perature. With  these  it  is  possible  to  get  a  casting  almost  the  size  of  the  flasked 
pattern,  but  absolutely  no  larger.  The  highest  reading  we  obtained  on  castings 
made  in  a  brass  flask,  and  at  a  temperature  almost  sufficient  to  fuse  the  flask,  was 
.4992  in.  from  a  pattern  of  .5000  in.  We  are  strongly  of  the  opinion  that  Dr.  Baker's 
patterns  were  not  the  size  he  supposed  them  to  be. 

Increased  specific  gravity  is,  indeed,  a  most  excellent  feature  in  an  inlay.  And 
we  do  not  take  issue  with  anyone's  statement  that  casting  in  a  cold  mold  increases 
the  specific  gravity  of  the  casting  thus  produced.  We  have  not  experimented  along 
this  line  but  we  know  that  this  condition  obtains  in  grey  iron.  Grey  iron  cast  against, 
or  in,  "chills,"  is  so  finely  crystalized  and  hard  that  it  cannot  be  cut  except  by 
grinding;  and  cannot  be  annealed  except  by  remelting.  If,  however,  the  increased 
specific  gravity  of  a  gold  inlay  be  obtained  at  the  expense  of  accuracy,  of  adaptation 
— which  feature  would  undoubtedly  obtain  from  shrinkage  if  cast  in  a  cold  mold — 
we  cannot  but  sec  that  as  a  whole  an  already  strong  point  has  been  strengthened, 
and  a  weak  point  made  weaker.  Namely,  the  density  of  any  gold  inlay  is  more 
durable  than  the  cement  line  which  surrounds  the  inlay.  Increased  specific  gravity 
can  be  obtained  to  a  sufficient  depth  on  the  masticating  surface  by  means  of  round 
or  corrugated  engine  burnishers, 


CASTING:  A    RETRCSTECT  95 

Quoting  again  from  Dr.  Baker,  in  the  article  prex'iously  referred  to,  "If  we  have 
a  step  cavity  with  a  good  dovetail  in  the  occlusal  we  find  that  that  dovetail  is  going 
to  draw  the  inlay  into  position  towards  the  occlusal  in  such  a  way  that  when  pressed 
down  or  hammered  into  place  in  the  best  possible  way  there  will  be  at  the  cervical 
a  heavy  line  of  cement  showing.  Why  is  that?  It  is  simply  because  the  cavity  is 
prepared  with  almost  parallel  sides,  and  if  this  inlay  is  the  same  size  as  the  cavity, 
the  cement  will  take  up  too  much  space,  so  that  it  raises  it."  Our  observations  in 
such  instances  have  shown  that  the  condition  as  described  is  not  due  to  its  close 
fit  in  the  cavity  and  the  interference  of  cement,  but  because  of  excessive  contraction 
of  the  inlay.  When  the  morsal  part  of  such  an  inlay  is  seated  on  its  foundation, 
the  approximal  part  is  not  long  enough  to  reach  its  destination  at  the  cervical  aspect 
of  the  cavity.  Also  that  the  part  fitting  into  the  dovetail  (if  this  dovetail  be  a  very 
pronounced  one)  is  so  contracted  that  it  will  not  allow  the  approximal  part  to  fit 
closely  against  the  pulpal  wall  of  the  cavity  except  at  the  angle  of  the  step.  This 
observation  may  easily  be  made,  and  the  facts  cited  determined,  by  placing  such  an 
inlay  in  the  cavity  without  cement,  and  see  exactly  the  condition  referred  to. 

We  believe  that  the  shrinkage  problem  in  cast  gold  inlays  is  net  generally  con- 
sidered as  important  as  its  clinical  results  will  warrant.  Quoting  from  Dr.  Ward, 
Dental  Cosmos,  Vol.  LI,  p.  1056:  "If,  then,  a  filling  1-4  in.  in  diameter  shrinks 
.0008  in.  and  is  seated  in  the  center  of  the  cavity,  there  will  be  .0004  in.  to  be  filled 
with  cement  on  each  side.  If  the  casting  be  a  compound  approximal  one  for  a  molar 
measuring  1-2  in.,  we  can  only  calculate  a  total  shortening  mesio-distally  of  .0016  in. 
Imagine,  if  you  will,  such  a  cavity  being  prepared  with  its  walls  inclining  sufficiently 
to  enable  one  to  draw  a  wax  impression,  and  a  filling  that  had  shortened  from  the 
extreme  ends  only  .0016  in.  Do  you  doubt  its  going  to  place?  It  will  do  it  so  clcselj' 
that  the  naked  eye  cannot  detect  it,  if  the  cavity  has  been  properly  prepared.  These 
figures  will  not  hold  good  for  casts  made  in  a  red-hot  mold,  or  if  the  gold  is  super- 
heated. They  hold  good  for  casts  made  of  gold  heated  above  its  melting  point,  and 
a  little  below  its  boiling  point,  and  cast  in  a  cool  mold."  Also  quoting  Dr.  Price, 
Items  of  Interest,  Vol.  XXX,  p.  933:  "In  bridge  work,  because  of  the  length  of  the 
piece,  the  cooling  contraction  not  only  makes  the  piece  too  short  to  reach  the  abut- 
ments, thereby  throwing  one  of  them  out  of  register,  but,  if  the  attachment  encloses 
a  foundation  as  a  ferrule  for  a  root,  its  decreased  diameter  will  not  allow  it  to  go  over." 
In  Dental  Cosmos,  Vol.  L,  p.  940,  (Hinman)  shows  a  cut  of  a  bridge  with  two  inlay 
anchorages.  Items  of  Interest,  Vol.  XXXI,  p.  815  (Reynolds),  shows  a  cut  of  a 
similar  bridge.  Dr.  Baker  in  the  article  referred  to  a  number  of  times,  says:  "  1-10000 
in.  in  the  size  of  an  inlay  larger  than  the  cavity  is  almost  fatal."  In  the  bridges 
referred  to,  a  shrinkage  of  18-100  of  one  per  cent,  would  put  the  inlay  anchorages  so 
much  out  of  register  that  they  would  not  seat  properly,  and  possibly  not  even  in- 
differently. The  double  compound  inlay  that  registers  a  shrinkage  of  .0016  in. — as 
cited  by  Dr.  Ward  in  the  above  quotation — would  certainly  not  go  into  place  unless 
it  was  forced  into  the  cavitj'  under  a  pressure  sufficient  to  actually  stretch  it.  This 
particular  kind  of  inlay  is  the  most  difficult  we  have  to  make;  and  one  wherein  the 
shrinkage  problem  looms  up  most  forcibly.  For  if  the  inlay  is  large  enough  to  nicely 
sit  astride  the  shallower  central  part  of  such  a  cavity  without  stretching,  it  would 
have  to  be  at  least  as  large  as  the  cavity.  If  such  an  inlay  is  absolutely  as  large 
as  the  cavity  it  will  not  go  in  and  seat  properly  for  the  other  dimensions;  and  par- 
ticularly so  when  we  reckon  the  space  necessary  for  the  cement  line.  One  dimension 
of  such  an  inlay  ought  to  be  a  trifle  larger  than  the  pattern;  and  the  other  dimension 


96  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

shorter.  This  condition  wc  know  would  be  impossible  to  obtain;  and  the  only  chance 
for  us  is  to  force  enough  stretch  into  it  to  allow  it  to  reach  over  the  interior  of  such 
a  cavity. 

We  are  firmly  of  the  opinion  that  the  investment  has  a  very  great  deal  to  do 
with  shrinkage,  or  lack  of  the  same.  An  investment  material  should  expand  suf- 
ficiently on  heating  to  follow  up  the  expansion  of  the  brass  flask  which  contains  it. 
With  such  an  investment  the  shrinlcage  can  easily  be  taken  care  of,  except  in  large 
bridge  castings.  During  the  autumn  of  '07  your  essayist  conducted  a  more  or  less 
exhaustive  series  of  experiments  in  an  effort  to  formulate  a  suitable  investment 
compound.  The  result  of  the  experiments  was  given  at  a  regular  meeting  of  the 
Pennsylvania  Association  of  Dental  Surgeons,  during  the  same  autumn,  and  also 
in  a  paper  read  at  San  Francisco  in  June,  '08: — a  record  of  which  is  in  the  Pacific 
Gazette,  Vol.  XVI,  p.  586.  The  best  results  we  obtained  were  gotten  in  a  compound 
made  up  of  cast  plaster  1  part,  and  very  finely  powdered  silex  3  parts  (by  weight). 
In  April  and  May,  '09,  we  conducted  a  series  of  experiments  to  obtain  data  on 
shrinkage  of  gold  castings.  Castings  made  in  Peck's  investment  compound  si;owed 
83-100  of  one  per  cent,  shrinkage;  S.  S.  White's  showed  18-100  of 
one  per  cent.,  and  in  silex  and  plaster  as  above  given,  we  had  only  16-100  of  one 
per  cent,  shrinkage.  These  figures  are  for  casts  made  in  hot  molds.  With  the  same 
investments  and  technique,  except  that  the  flasks  were  allowed  to  cool  to  a  tem- 
perature which  allowed  handling  with  the  fingers,  we  had  a  loss  of  1.64  per  cent,  by 
shrinkage  in  the  plaster  and  silex  investment,  and  proportionately  more  with  the 
other  investments  mentioned. 

Quoting  from  your  essayist.  Pacific  Gazette,  Vol.  XVI,  p.  589:  "A  smoother 
casting  is  obtained  if  the  investment  has  been  allowed  to  remain  some  hours,  or  even 
days,  before  heat  is  applied."  While  this  idea  is  all  right  for  the  purpose  stated  we 
find  that  if  a  flask  is  allowed  to  stand  a  long  time  before  casting  we  have  a  marked 
increase  in  the  shrinkage  of  the  casting  made  in  such  a  mold.  We,  therefore,  find  it 
advisable  to  choose  the  least  evil,  and  cast  within  a  few  hours,  at  most,  after  investing. 

We,  with  others,  believe  that  the  time  will  come  when  the  perfection  of  casting 
devices  will  make  it  possible  for  us  to  pre-determine  the  amount  of  shrinkage. 
Quoting  Dr.  Baker,  Dental  Reviezv,  Vol.  XXIV,  p.  130:  "  I  believe  that  the  time  will 
come  when  we  can  control  the  size  of  the  cast  we  want  by  the  temperature  of  our  in- 
vestment. When  we  get  this  work  down  to  a  certain  pcint  we  will  need  a  thermostat 
to  tell  the  temperature  of  our  investment  when  we  cast  in  order  to  get  the  size  we 
want."  Quoting  your  essayist,  Dental  Digest,  Vol.  XV,  p.  499:  "It  yet  remains 
for  some  genius  to  devise  a  form  of  casting  apparatus  with  a  pyrometer  attachment 
to  indicate  the  temperature  of  the  flask  while  casting;  this,  in  conjunction  with  an 
investment  material  of  known  physical  properties  could  be  a  means  of  accurately 
determining  the  relative  size  of  the  casting." 

We  believe  that  a  misconception  is  more  or  less  generally  extant  in  regard  to 
why  any  pressure  should  be  needed  to  place  and  hold  the  molten  gold  in  the  mold 
in  casting,  the  commonly  accepted  idea  being  that  the  pressure  used  is  needed 
because  of  air  and  gases  within  the  mold.  Quoting  Dr.  Trigger,  Dental  Brief,  July, 
'09,  p.  469:  "In  order  to  force  the  molten  gold  into  such  a  mold  already  described 
it  requires  a  pressure  exerted  on  the  metal  in  the  molten  state  to  overcome  the 
atmospheric  pressure  of  air  within  the  mold,  that  is,  the  force  on  the  gold  muse  more 
than  equalize  the  air  within  to  allow  it  to  flow  readily  to  all  parts."  According  to 
experiments  which  we  conducted  we  believe  that  air  or  gas  resistance  has  so  little 


CASTING:  A  RETROSPECT  97 

to  do  with  the  need  of  pressure  that  it  need  not  be  taken  into  consideration.  Quoting 
your  essayist  from  the  Dental  Digest,  Vol.  XV,  p.  498:  "The  only  reason  why  any 
pressure  is  needed  is  that  the  molecular  attraction  that  holds  a  mass  of  molten  gold 
in  globular  or  spheroidal  form  is  greater  than  the  force  of  gravity;  the  gold,  therefore, 
will  not  by  force  of  gravity  change  its  spheroidal  form  and  flow  down  into  a  mold 
without  assistance."  The  experiment  which  proved  this  consisted  in  preparing  a 
flask  with  investment  material  in  such  a  manner  that  the  sprue  opening  extended 
entirely  through  the  bottom  of  the  investment  and  flask.  The  flask  was  heated  to 
redness — ^as  if  for  casting — placed  on  a  support  so  arranged  that  anything  that 
wanted  to  go  through  the  sprue  opening  would  have  no  interference  from  within  or 
underneath,  and  gold  fused  in  the  crucible.  There  was,  indeed,  under  such  conditions 
no  air  resistance  from  within  or  underneath;  but  gold  fused  in  the  crucible  immediately 
over  the  sprue  did  not  drop  through  the  opening.  Varying  amounts  of  gold  were 
tried:  2,  33^  and  514.  dwt.  The  first  sprue  opening  tried  was  of  standard  size  for 
practical  work — .055,  or  a  trifle  smaller  than  15  gauge.  The  gold  was  heated 
by  the  oxy-hydrogen  blow-pipe  until  volatilization  began.  If  the  flask  was  raised 
a  couple  of  inches  and  set  down  with  a  jolt  the  gold  would  then  run  through.  The 
size  of  the  sprue  opening  was  increased  by  known  stages  until  it  was  .120  in.  (almost 
1-8  of  an  inch)  before  the  gold  would  run  down  of  its  own  accord  when  melted — 
and  even  then  only  when  heated  to  a  temperature  quite  beyond  its  fusing  point. 

We  believe  that  the  margins  of  an  inlay  should  be  thoroughly  burnished  to  the 
cavity  margins  as  soon  as  cemented  in,  and  before  the  cement  has  become  friable. 
And  in  order  that  the  burnishing  may  be  effective  as  a  means  to  an  end,  the  wax 
pattern  must  have  been  prepared  without  any  overlap  whatever.  If  an  overlap  is 
present,  it  is  the  overlapping  part  that  receives  the  burnishing,  and  which  is  after- 
ward cut  away  in  the  finishing.  What  is  then  the  edge  of  the  inlay  has  not  been 
affected  by  burnishing  at  all. 

The  cementing  and  finishing  of  an  inlay  should  be  completed  at  the  same  sitting, 
and  before  the  cement  has  attained  its  utmost  density.  We  believe  that  it  is  possible 
for  the  heat  caused  by  the  friction  of  grinding  stones  to  be  in  some  cases  sufficient 
to  cause  expansion  of  the  parts  involved;  the  inlay  having  a  very  different  coefficient 
of  expansion  from  that  of  the  cement  and  tooth  under  it  may  cause  some  areas  to 
actually  break  the  heterogeneous  union.  Before  the  cement  has  become  fully 
hardened  its  physical  properties  would  allow  for  this  unequal  expansion  without  risk 
of  fracture.  This,  purely  theoretical,  having  no  data  on  the  subject;  but  we  believe 
that  it  is  possible  for  this  condition  to  obtain.  As  stated  earlier  in  this  paper,  the 
desired  specific  gravity  on  the  surface  may  be  obtained  by  the  generous  use  of  engine 
burnishers  of  steel  or  agate,  or  still  better,  of  corrugated  steel. 

After  noting  the  vast  differences  of  opinion  that  we  have  quoted  and  referred 
to,  we  may  in  our  perplexity  well  wonder,  as  did  Pape  in  his  "Moral  Essays" — "Who 
shall  decide  when  doctors  disagree?" 

DISCUSSION 

Dr.  E.  B.  Lodge,  Cleveland,  O.:  I  will  take  this  opportunity  first  to  thank  tlie  program  com- 
mittee for  allowing  my  name  to  appear  in  connection  with  that  of  our  essayist,  Dr.  Lane. 

The  subject  is  a  most  timely  one  and  one  which  must  elicit  the  attention  of  all  dentists  desirous 
of  attaining  the  best  results  for  their  patients.  In  much  that  the  essayist  has  said  I  most  heartily  agree, 
but  there  are  some  things  which  I  cannot  indorse. 

Quoting  from  the  essayist's  paper,  he  says,  "In  any  transfer  we  can  scarcely  avoid  losing  detail 
and  definition,  therefore  the  fewer  the  transfers  the  better  tlie  inlay  is  going  to  fit,  all  other  things  being 
equal," 


98  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Now.  there  are  none  who  will  not  agree  to  this  statement,  as  in  it  the  essayist  is  perfectly  right, 
but  he  tells  us  "the  pattern  for  a  gold  inlay  should  be  made  in  the  cavity  that  is  to  receive  the  finished 
casting,  that  it  involves  but  three  transfers,  cavity  to  pattern,  pattern  to  investment,  and  investment 
to  gold."  The  model  method  where,  for  example,  we  have  an  amalgam  model,  he  tells  us  that  we  have 
live  transfers,  "cavity  to  impression,  impression  to  model,  model  to  pattern,  pattern  to  investment, 
and  investment  to  gold,"  and  again  to  quote,  "or  if  the  casting  is  done  directly  in  the  model,  we  still 
have  four  transfers  by  the  latter  method." 

Just  here  I  must  object;  since  the  model  made  in  the  impression  becomes  a  part  of  the  investment, 
how  can  it  entail  another  transfer  of  cavity  surfaces  than  when  a  wax  pattern  is  invested?  Dr.  Lane 
is  in  error,  for  each  process  entails  only  three  transfers  of  cavity  surface.  Then,  too,  in  securing  the 
occlusal  dimensions  the  patient  can  close  his  teeth  upon  a  piece  of  softened  wax  as  readily  as  he  can 
close  upon  a  wax  pattern  within  the  cavity. 

Few  operators  can  carve  a  wax  pattern  for  a  compound  cavity  within  the  mouth  in  even  ten  times 
the  time  required  to  carve  a  very  accurate  one  upon  a  stone  model  of  the  case,  by  which  method  is 
avoided  the  almost  impossible  task  of  carving  exact  contours  and  margins  under  the  gingival  tissue  in 
a    difficult    environment. 

This  method  obviates  also  the  possibility  of  the  wax  pattern  lifting  up  at  one  side  when  pressed 
down  upon  the  opposite  side  as  is  so  liable  to  happen  in  the  direct  method.  I  should  like  to  ask  further 
how  the  essayist  would  get  the  needed  pressure  on  his  contact  point  without  extra  work 

How  by  the  direct  method  can  an  operator  reproduce  several  contact  points  at  once  or  even  two 
adjoining  and  get  them  accurate?  (Here  I  show  set  of  models,  one  showing  inlays  with  five  contact 
points  and  two  double  compound  cavities.)  Just  figure  the  difference  in  time  carving  them  all  up  in 
the  cavities  and  taking  one  impression  of  them  all  in  a  few  seconds.  Can  any  man  produce  as  perfect 
contours  by  carvmg  in  the  wet  mouth  as  the  finished  model  shows?  All  those  restorations  were  inserted 
together. 

How  does  the  essayist  hold  the  inlay  in  pohshing?  How,  in  polishing,  does  he  prevent  spinning 
of  the  margins?  How,  too,  does  he  prevent  the  gold  from  shortening  mesio-distally  in  a  double  com- 
pound cavity,  and  how  does  he  correct  for  distortion  of  the  cavity  surface  due  to  pressure  upon  the 
investment? 

And  how  is  he  able  to  differentiate  between  expansion,  distortion  of  the  investment  and  expansion 
of  the  cooling  gold  or  decrease  of  normal  contraction  due  to  pressure  e.xerted? 

That  a  distortion  does  result  from  the  pressure  exerted  upon  the  investment  from  within  at  the 
time  of  casting  is  a  demonstrable  fact.  This  is  overcome  by  the  use  of  the  artificial  stone  model.  Its 
rigidity  enables  it  to  withstand  any  amount  of  pressure  that  may  be  desired  without  distortion  and  con- 
sequent change  of  shape  of  the  resulting  inlay. 

One  point  further  in  the  advocacy  of  the  model  method,  greater  accuracy  of  adaptation  is  assured, 
particularly  in  compound  and  double  compound  cavities,  by  the  taking  of  an  impression  in  a  suitable 
wax  and  specially  adapted  tray  to  hold  same,  and  I  believe  there  is  less  likelihood  of  distortion  in  the 
removal  from  the  teeth  of  such  a  tray  with  its  wax  impression  than  there  would  be  in  removing  a  wax 
pattern  directly  from  such  a  cavitj'. 

Dr.  Price  has  shown  and  I  will  quote  his  exact  words,  "the  total  contraction  of  a  definite  part  of 
cooling  mass  of  any  metal  or  alloy  can  be  materially  lessened  by  the  application  of  pressure  to  another 
part  of  the  same  coohng  mass.  This  causes  most  of  the  contraction  to  occur  in  one  place  where  not 
objectionable.  As  the  contraction  takes  place  the  mass  is  moved  by  the  pressure  at  a  certain  point  to 
replace  the  shrinkage  taking  place  elsewhere,  but  this  can  only  occur  so  long  as  the  pressure  is  greater 
than  the  resisting  strength  of  the  mass,  which  for  available  pressure  for  our  use  is  only  a  few  hundred 
degrees." 

"By  this  means  we  can  with  only  one-fiftieth  of  an  ounce  actual  pressure  reduce  the  total  con- 
traction in  part  of  a  mass  of  pure  gold  from  22.5  thousandths  to  20.5  thousandths  and  with  one-tenth 
ounces  reduce  it  to  18  thousandths.  With  three  pounds  we  may  reduce  it  to  1-i  thousandths  and  with 
five  and  one-half  pounds  to  13  thousandths.  Remember  that  the  actual  pressure  is  not  represented  by 
the  surface  pressure  per  square  inch  of  a  gas  pressing  upon  it." 

To  quote  still  further,  "The  other  methods  of  correcting  this  contraction  are  by  modifying  the 
alloy  to  have  a  minimum  contraction  (in  which  as  yet  but  little  has  been  done  but  no  doubt  will  be)  and 
by  either  enlarging  the  mold  so  that  the  cast  will  be  the  correct  size  when  contracted,  or  by  holding  the 
metal,  compelling  it  to  stretch  when  cooHng,  or  both.  This  can  be  accomplished  by  expanding  the  mold 
into  which  the  cast  will  be  made,  and  the  latter  only  where  the  metal  can  be  confined  over  a  very  strong 
form,  as  a  ring  around  a  very  hard  core. 

"The  expansion  of  the  mold  has  been  accomplished  to  a  certain  but  not  sufficient  extent  by  heating 
an  investment  material  forming  a  mold  and  casting  into  it  when  hot.  The  best  of  these  only  allow  an 
expansion  by  this  method  of  six  or  eight  thousandths,  and  most  investment  materials  very  much  less 


CASTING:  A  RETROSPECT  09 

if  not  an  actual  contraction  on  heating  and  this  class  of  material  on  heating  being  chiefly  silica  and 
plaster,  has  so  little  resistance  or  strength  that  it  is  easily  distorted  by  high  pressure,  absolutely  limiting 
the  use  of  the  first  named  method  for  preventing  the  contraction,  viz.,  by  making  high  pressure  on 
another  part  of  the  cooling  mass,  for  they  yield  producing  beads  and  distortion  on  the  surfaces,  which 
if  on  the  cavity  surfaces  of  the  inlay,  spoil  it.  The  ideal  conditions  demand,  then,  that  into  the  mold 
into  which  we  cast,  all  surfaces  that  are  ta  make  contact  with  cavity  walls  and  margins  be  so  hard  and 
strong  that  they  will  allow  of  high  pressure  without  yielding  and  should  expand  either  when  heated  or 
setting,  or  both,  to  increase  its  dimensions  uniformly  about  1.5  thousandths  which  is  one  and  one-half 
per  cent. 

"When  casting  upon  this  with  an  actual  pressure  of  about  two  and  one-half  pounds,  we  will  have 
a  cast  within  about  one  thousandth  the  dimensions  of  the  original." 

Now  I  might  say  something  about  the  use  of  the  cold  mold,  but  suffice  it  to  say  that  with  the 
present  investments  molds  contract  on  cooling  from  5  ten-thousandths  to  35  ten-thousandths,  according 
to  the  investment  employed,  less  than  their  size  prior  to  heating,  which  only  serves  to  accentuate  the 
contraction  of  inlays  cast  in  such  a  mold. 

I  have  the  opportunity  here  today  to  extol  this  fellow  townsman  and  a  most  unselfish  co-worker  in 
the  field  of  dentistry.  Dr.  Weston  A.  Price,  a  man  who,  like  Dr.  Black,  was  so  worthily  eulogized  at 
yesterday's  session  by  our  fellow  member.  Dr.  Friesell.  Just  as  Dr.  Black  has  brought  out  of  chaos 
into  systematized  practice  the  field  of  operative  dentistry  by  determining  the  causes  of  failure  in  the 
filling  of  teeth  and  in  finding  and  proclaiming  an  adequate  remedy,  so  has  Dr.  Price  been  an  indefatig- 
able worker  in  the  study  of  the  subject  of  the  gold  inlay;  not  only  is  he  a  blazer  of  trails  in  this  de- 
partment of  operative  dentistry,  but  I  am  sure  you  will  all  agree  with  me  that  he  towers  head  and 
shoulders  above  the  rank  and  file  even  of  the  small  minority  of  the  profession  who  attend  dental  society 
meetings. 

Some  one  has  said,  "Show  me  the  books  a  man  reads  and  I  will  tell  you  the  kind  of  man  he  is." 
We  will  all  agree,  I  think,  that  this  holds  true  equally  with  the  kind  of  friends  he  selects,  and  if  perchance 
he  be  a  dentist,  even  by  the  kind  of  instruments  he  employs. 

1  was  once  visiting  a  dentist's  office  and  I  happened  to  see  his  set  of  excavators  and  behold!  what 
a  mess  of  rubbish  they  were,  but  not  merely  that,  they  were  so  dull  that  I  questioned  whether  they  had 
seen  an  Arkansas  stone  since  they  left  the  manufacturers.  I  instinctively  put  that  man  down  as  one 
not  to  be  emulated. 

Now,  if  good  instruments  are  to  be  the  gauge  of  excellence,  let  us.  or  those  of  us  who  have  not  done 
so,  not  only  adopt  the  beautiful  instruments  of  Dr.  Black's  designing,  founded  upon  experience,  with 
angles  and  dimensions  all  scientifically  determined  with  great  exactness  for  the  work  they  are  to  per- 
form, but  let  us  also  adopt  as  an  instrument  for  saving  teeth,  the  artificial  stone  suggested  and  advocated 
by  Dr.  Price. 

Closing  remarks  of  the  essayist: 

Mr.  Presjdent  and  Gentlemen:  We  are  exceedingly  sorry  that  train  time  for  our  departure  is 
so  near  at  hand  that  the  discussion  of  the  paper  under  consideration  could  not  be  prolonged;  there  being 
yet  many  points  upon  which  we  should  like  to  have  heard  an  expression  of  opinion.  The  operation  of 
casting  is  as  standard  as  any  of  our  present  day  operations,  and  the  problems  which  it  involves  merit 
the  most  thorough  attention  and  research  possible.  A  comparison  of  differences  of  opinion  on  the 
subject  is — from  an  educational  standpoint — second  only  to  exhaustive  scientific  experimentation. 
In  order  that  the  result  of  experiments  may  obtain  as  a  means  to  an  end,  such  experiments  must  be.  or 
have  been,  conducted  along  lines  that  are  strictly  scientific,  and  in  absolute  accord  and  harmony  with 
such  laws  of  physics  as  are  known  to  be  inflexible. 

Dr.  Lodge  has  indeed  given  us  much  material  for  consideration,  and  has  presented  it  in  true  masterly 
fashion.  His  discourse  is  largely  in  the  nature  of  an  interrogation.  We  welcome  the  interrogation, 
and  would  have  preferred  it  to  have  included  many  other  points.  We  have  jotted  down  the  various 
questions  asked  by  Dr.  Lodge  as  well  as  we  could  get  them  in  hurried  fashion,  and  if  we  have  failed  to 
get  them  all  will  call  upon  Dr.  Lodge  to  restate  such  as  are  not  in  evidence. 

Dr.  Lodge  seems  to  be  a  firm  advocate  of  the  "indirect"  or  impression  method,  and  takes  exception 
to  our  statement  that  by  the  impression  method  there  are  too  many  transfers.  He  states  that  by  cast- 
ing in  a  model  of  artificial  stone  the  number  of  transfers  is  the  same  as  by  the  "direct"  or  pattern 
method.  This  is  not  correct.  The  little  joker  which  he  interposes  in  saying.  "The  model  made  in  the 
impression  becomes  a  part  of  the  investment."  almost  conceals  the  truth.  Unless  it  was  all  of  the  in- 
vestment his  criticism  does  not  hold  good,  and  the  best  he  can  do  is  three  transfers  for  a  part  of  his 
wax  pattern,  and  four  for  the  balance  of  it — as  against  three  transfers  throughout  by  the  direct  method. 
The  number  of  transfers  by  any  method  is  of  less  consequence  than  the  integrity,  or  questionability  of 
such  transfers,  or  the  possible  element  of  inaccuracy  in  handling  the  transfers,  and  we  must  still  insist 
that — as  stated  in  the  paper — there  is  vastly  more  possibility  of  distortion  in  an  impression  than  in  a 


100  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

pattern,  and  for  the  reasons  stated.  We  all  know  that  a  plaster  impression  is  almost  invariably  broken 
while  being  removed  from  the  teeth — even  though  that  impression  includes  a  very  small  area.  Why 
does  it  break?  Because  the  shape  of  the  tooth,  or  teeth,  is  such  that  the  rigid  plaster  cannot  come  off 
over  larger  portions  of  the  tooth,  or  teeth,  or  follow  varying  axial  lines  of  the  enclosed  teeth,  without 
breaking.  The  same  condition  that  breaks  a  plaster  impression  bends  a  wax  or  compound  one.  Grant- 
ing that  the  outer  surfaces  of  the  teeth  and  the  interproximal  spaces  are  of  such  shape  that  an  impression 
would  draw  without  bending  or  breaking,  it  yet  remains  that  the  prepared  cavities  in  those  teeth  must 
have  exactly  the  same  line  of  draught.  This  latter  is  a  very  exceptional  condition,  and  when  obtained 
at  all,  it  is  usually  an  unnecessary  expense  of  tooth  structure. 

The  models  shown  by  Dr  Lodge  show  beautiful  work.  Articulation  and  contact  points  just  right. 
And  the  inlays  fit  the  cavities  absolutely.  Naturally,  having  been  cast  therein,  and  not  removed 
since.  But,  how  can  any  one  here  determine  by  examining  these  models  whether  the  impressions 
in  which  they  were  made  were  distorted  or  not?  If  this  model  is  accurate,  then  the  impression  in  which 
it  was  made  must  have  been  accurate;  if  the  wax  impression  was  accurate  then  the  teeth  over  which 
it  was  taken  must  have  had  no  contour — or  at  least  could  not  have  been  larger  at  the  coronal  portion 
than  at  the  gum  line;  al)  the  teeth  included  must  have  had  their  axial  lines  parallel;  all  the  prepared 
cavities  must  have  had  their  lines  of  draught  exactly  parallel  with  each  other,  and  all  parallel  with  the 
long  axes  of  the  teeth.  Can  we  conceive  of  finding  such  a  condition  in  ordinary  practice  more  than 
once  or  so  in  a  lifetime?  And  unless  the  conditions  as  enumerated  are  present  in  a  given  case,  distortion 
of  a  wax  impression  must  be  expected — even  with  all  the  preventive  possibilities  that  the  neat  little 
trays  can  provide. 

Dr.  Lodge  tells  us  that  a  pattern  can  be  made  quicker  in  a  model  than  in  a  tooth.  In  some  cases 
this  can  easily  obtain.  But  when  we  consider  the  extra  operations — such  as  taking  an  impression, 
taking  a  bite,  making  a  model  and  fusing  it,  placing  the  model  and  bite  on  an  articluator — we  are  then, 
by  the  impression  method,  only  ready  to  begin  the  same  routine  of  operations  that  would  entirely 
complete  the  case  by  the  pattern  method.  Time  is  money.  Either  the  patient  or  the  operator  must 
lose  by  the  slower  method. 

Dr.  Lodge  asks  how  we  would  get  the  needed  pressure  on  the  contact  point.  We  do  this  by  in- 
serting the  sprue  wire  at  this  point.  The  sprue  wire  we  use  for  ordinary  work  is  0.070  in.  The  extra 
pressure  for  the  contact  point  is  thus  gotten  without  any  extra  operation,  or  apparatus. 

Dr.  Lodge  also  asks  how  adjoining  contact  points  can  be  gotten  by  the  direct  method.  There 
are  various  ways.  One  is — press  pattern  wax  into  both  cavities;  bite,  rough  trim,  and  separate  the 
two  with  a  thin  ribbon  saw;  then  finish  each  separately  while  the  other  is  in  position.  Place  the  sprue 
wire  in  each  at  the  contact  point  to  get  the  needed  pressure.  Another  method  is — first  make  one 
pattern,  and  while  it  is  in  place  adjust  an  oiled  matrix  to  the  other  cavity,  and  make  the  second  pattern 
in  it.  (An  "Ivory"  matrix  works  very  well  for  this.)  Place  sprue  wires  as  stated.  Still  another, 
method  is — that  one  cavity  can  be  completed  at  a  time. 

Dr.  Lodge  asks  how  we  hold  the  inlay  while  polishing.  We  do  not  hold  it  while  polishing,  having 
always  maintained  that  the  only  proper  place  to  polish  an  inlay  is  in  the  tooth  after  cementation. 
We  do  whatever  shaping  is  necessary  where  the  riser  is  cut  off,  while  holding  the  inlay  in  our  fingers; 
using  great  care  to  not  even  approach  a  margin.  An  inlay  is  not  ready  to  be  polished  until  it  has  been 
cemented  in  the  cavity,  and  its  margins  burnished  before  the  cement  has  become  friable. 

Dr.  Lodge  also  asks  how  we  prevent  the  gold  from  shortening  mesio-distally.  This  is  accomplished 
the  same  as  for  any  other  dimension.  As  stated  in  the  paper,  it  is  easily  possible  to  make  a  casting 
in  the  investment  given,  that  has  a  shrinkage  of  only  .16  of  1  per  cent.  Granting  that  we  have  a 
casting  that  has  a  zero  measurement  (no  shrinkage),  we  could  not  seat  it  in  cement.  Cement  occupies 
space.  As  stated  in  the  paper,  one  dimension  of  an  inlay  for  a  double  compound  cavity  should  be  a 
trifle  larger  than  the  cavity,  and  the  other  dimension  smaller  than  the  cavity.  There  is  as  yet  no 
means  of  bringing  about  such  a  condition.  The  pattern  for  such  an  inlay  can  be  cut  away  from  under 
the  center  until  the  resultant  casting  will  stretch  enough  to  allow  for  what  little  may  be  necessary. 

Dr.  Ivodge  asks  how  we  correct  for  distortion  of  the  cavity  surface  due  to  pressure  upon  the  invest- 
ment. We  obviate  the  need  of  any  correction  by  using  a  definite  pressure  that  does  not  distort  the 
mold.  We  cast  under  a  pressure  of  25  lbs.  (air  pressure)  per  square  inch.  And  having  tested  our 
investment  up  to  45  lbs.,  we  know  that  we  are  absolutely  safe  at  the  former  figure.  Furthermore, 
high  pressures  are  not  necessary.  The  only  argument  ever  advanced  in  favor  of  high  pressure  is  that 
shrinkage  can  be  partly  overcome  by  that  means.  We  have  experimented  with  pressures  ranging 
anywhere  from  sharp  margins  (5  lbs.  per  square  inch)  to  the  strength  of  our  investment  (45  lbs.  per 
square  inch)  and  in  that  range,  any  variation  in  contraction  due  to  varying  pressures  could  not  be 
detected  by  a  vernier  micrometer.  Inasmuch  as  by  the  artificial  stone  method  a  part  of  the  mold  is 
made  of  ordinary  investment  material.  Dr.  Lodge's  question  would  apply  to  that  method  as  well. 
Beads  on  a  casting  do  not  indicate  a  distorted  mold.     They  indicate  faulty  technique  in  placing  the 


CASTING:  A   RETROSPECT  lOl 

investment  material  on  tlie  pattern.  The  same  could  obtain  in  placing  the  compound  for  an  artificial 
stone  model  in  the  impression.  Undue  pressure  will  force,  or  distort,  a  mold  as  a  whole.  Not  as 
l>eads.     Beads  will  not  form  unless  the  spaces  for  them  are  already  there. 

Dr.  Lodge  quotes  Dr.  Price  on  pressures,  contraction,  etc.  While  we  must  admit  that  Dr  Price 
has  worked  out  a  beautiful  technique  on  theory,  yet  we  have  not  been  able  to  obtain  from  his  writings 
— and  we  believe  we  have  read  most,  or  all,  of  them —  certain  data,  or  technique,  that  must  of  necessity 
belong  in  order  that  his  technique  may  obtain  as  he  claims  for  it.  This  data  is — the  lemperalure  thai 
the  mold  must  have  at  the  moment  of  casting,  and  a  means  of  determining  that  temperature.  Dr.  Price  has 
ingeniously  devised  an  artificial  stone  that  has  a  permanent  expansion  equal  to  the  normal  expansion 
of  gold  up  to  its  fusing  point.  Granting  this  equalization,  then  any  rise  in  temperature  in  the  flask  at 
the  moment  of  casting  means  an  increase  in  the  size  of  the  casting  over  and  above  zero  measurement. 
In  order  to  roughly  demonstrate  to  you  the  effect  of  variation  of  temperature  in  the  flask  at  the  moment 
of  casting,  we  have  here  a  small  mandrel  on  which  are  two  gold  rings.  The  mandrel  has  a  taper  of 
1  degree;  the  patterns  for  the  rings  shown  here  were  made  at  exactly  the  same  point  on  the  mandrel; 
both  were  invested  in  the  investment  material  that  we  have  advocated,  and  from  the  same  mix,  or  bowl 
of  batter.  There  could,  therefore,  be  no  possible  difference  in  physical  conditions  thus  far.  One  ring 
was  cast  in  a  mold  as  hot  as  the  fusing  point  of  the  brass  flask  which  contained  it  would  allow,  and  the 
other  cast  in  a  flask  that  was  cool  enough  to  handle  with  the  fingers  at  the  moment  of  casting.  You  will 
notice  that  one  ring  drops  to  within  the  tiniest  line  of  the  point  where  the  patterns  were  made,  and  the 
other  ring  stops  about  3-8  of  an  inch  further  up.  Therefore,  in  order  to  make  a  given  technique  com- 
plete, data  for  the  temperature  of  the  flask  at  the  moment  of  casting  should  be  given. 

The  figures  given  us  by  Dr  Lodge — giving  the  eft'ect  of  pressure  as  determined  by  Dr  Price — are 
in  error.  Dr.  Price  obtained  these  figures  by  experimenting  in  casting  with  a  centrifugal  machine. 
In  the  same  article  in  the  Items  of  Interest,  wherein  Dr.  Price  gives  us  these  figures,  he  states  that  in 
computing  pressure  in  such  a  machine,  the  entire  mass  of  gold  in  the  crucible  is  available,  and  must 
be  reckoned  in  computing  the  pressure  on  the  sprue  area.  This  is  unquestionably  an  error.  An 
inflexible  law  of  physics  teaches  us  that  the  only  bulk  of  gold  available  for  pressure  and  computation, 
under  such  conditions,  is  a  bulk  equal  to  the  area  of  the  narrowest  part  of  the  sprue  opening,  and  the 
length  of  which  is  the  height  of  gold  in  the  crucible.  All  the  remaining  bulk  of  gold  that  fills  the  rest  of 
the  funnel-shaped  crucible  adds  absolutely  nothing  to  the  pressure  on  the  actual  sprue  area.  Therefore, 
all  the  figures  that  are  based  on  this  theory  and  method  of  computation,  are  certainly  in  error.  We 
recall  having  seen  cuts  of  a  device  that  was  to  produce  perpetual  motion,  and  will  sketch  the  same  on 
the  blackboard.  The  device  is  a  funnel-shaped  receptacle,  having  a  long  curved  neck  or  spout,  that 
curves  aside,  upward  past  the  body  part,  and  again  curving  so  as  to  have  its  final  opening  directly 
over  and  pointing  toward  the  open  top  of  the  larger  or  funnel  part.  The  belief  was,  that  water  placed 
in  the  large  part  of  the  device  would  exert  so  much  force  through  the  small  curved  spout  that  a  con- 
tinuous flow  would  be  established  around  and  into  the  original  receptacle.  Of  course,  it  did  not 
work,  and  for  the  reason  we  have  mentioned. 

As  we  stated  a  few  moments  ago,  unless  all  these  experiments  are  worked  out  on  a  truly  scientific 
basis,  and  in  strict  harmony  with  the  known  inflexible  laws  of  physics,  such  research  can  avail  little  or 
nothing,  as  a  means  to  an  end. 


102  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

CAST  PINS  FOR  CROWNS 

By  W.  A.   Stewart,  D.D.S.,   Kansas  City,  Mo. 

This  pin  is  to  be  used  when  and  where  a  pin  is  needed  in  a  tooth;  for  example, 
a  Richmond  crown,  to  help  anchor  inlays,  in  broken  down  teeth,  or  to  be  used  in 
root  or  roots  of  molars  that  are  to  be  built  up. 

ADVANTAGES 

1.  It  is  tailor-made  and  fits. 

2.  No  part  of  the  tooth  is  taken  away  that  is  not  filled  by  the  pin. 

3.  It  tapers,  making  it  the  shape  of  the  root,  and  does  not  weaken  the  tooth  at 
farther  end  of  pin,  leaving  it  plenty  large  enough  at  the  other  end. 

4.  Never  fits  until  it  is  in  place,  leaving  plenty  of  room  for  cement  to  be  dis- 
placed. 

5.  The  pin  is  made  before  the  patient  comes,  and  will  fit  as  soon  as  it  is  placed 
in    the    canal. 

6.  Always  stays  in  place  while  working  around  it  before  it  is  cemented. 

7.  Impression  is  not  taken  in  wax. 

DIRECTIONS   TO   MAKE 

Fill  the  ring  with  investment  and  let  it  dry;  drill  a  hole  with  reamer  in  invest- 
ment, then  cast;  drill  a  hole  in  the  tooth  with  the  same  reamer,  any  depth  desired; 
try  pin  in  and  see  that  it  fits;  if  it  is  too  long  cut  it  off.      I  use  22k.  gold. 


A  METHOD  FOR  CASTING  BACKINGS  FOR  ALL-PORCELAIN  FRONTS 
FOR  CROWNS  AND  BRIDGES 

By  D.  Haight,  Coshocton,  Ohio. 

Take  any  of  your  old  cast-off  facings  or  broken  plate  teeth  that  have  no  pins,  of 
any  shade  that  will  suit  the  case,  or  a  Steele  facing,  and  grind  flat  like  a  Steele  facing. 
Grind  it  on  the  cutting  edge  as  sharp  and  thin  as  you  can.  Grind  ofT  the  cutting 
edge  to  be  supplied  the  same  length  you  would  grind  the  porcelain  for  a  gold  tip. 
Take  a  knife-shaped  carborundum  stone  and  cut  a  groove  lengthwise  about  the 
depth  of  a  Steele  facing,  having  the  walls  parallel.  Take  inlay  wax,  shape  it  as  you 
want  your  backing,  and  have  a  good  tip  on  cutting  edge,  for  these  are  the  secrets 
of  success;  then  remove  and  cast.  After  it  is  cast  cut  serrations  in  the  gold  lug  with 
a  knife-edge  carborundum  and  cut  little  undercuts  in  groove.  See  that  your  facing 
fits  perfectly  to  the  backing.  When  you  use  for  bridge  or  crown  work,  just  before 
you  invest,  be  sure  and  use  antiflux  so  that  no  solder  will  run  where  your  facing 
goes.  I  find  Harvard  cement  the  best  for  cementing  the  porcelain  to  the  backing. 
I  have  had  perfect  success  with  this  work  for  over  fifteen  years.  By  burnishing 
platinum  on  facing,  the  same  as  porcelain  filling  process,  but  since  the  process  of 
casting,  it  is  much  more  simple.  In  case  of  breaking  one  out  another  can  be  ground 
in  without  taking  off  the  bridge. 


RESTORATION  OF  BADLY  BROKEN-DOWN  ROOTS  WITH  ACOLITE 

By  James  B.  Lester,  D.D.S.,   Christianburg,   Virginia. 

The  saving  of  badly  decayed  roots  is  a  thing  too  often  neglected  by  the  dentist. 
I  have  reference  to  those  roots  where  decay  has  progressed  far  be^'ond  the  cer\ucal 
portion. 

In  my  judgment  the  condition  of  these  teeth  arises  from  one  of  two  principal 
causes;  first,  many  persons  fail  to  realize  the  importance  of  caring  for  the  teeth  until 
they  are  badly  broken  down,  and  then  they  present  themselves  for  extraction  because 
of  alveolar  abscess;  second,  many  people  are  too  miserly  to  have  their  teeth  cared  for 
until  they  have  lost  a  large  number,  and  they  realize  their  inability'  to  properh' 
masticate  their  food. 

The  first  class  can  generally  be  convinced  of  the  importance  of  caring  for  their 
teeth.     The  second  are  easily  convinced  that  their  teeth  are  important  to  them. 

In  mouths  of  this  class  of  patients  we  often  find  rocts  that  are  covered  with  gum 
tissue.  After  the  decay  is  removed  the  end  cf  the  root  is  beyond  the  cervical  line, 
hence,  in  my  opinion,  it  cannot  be  restored  with  any  material  that  is  placed  there  in  a 
plastic  condition,  because  it  would  be  impossible  to  make  a  restoration  smooth  and 
of  proper  contour  be^'ond  the  gum  line. 

Because  the  restoration  of  these  roots  to  their  normal  usefulness  is  tedious, 
many  dentists  condemn  them  to  the  forceps  and  replace  with  bridges. 

In  my  practice,  if  there  is  two-thirds  or  three-fourths  of  a  root  left  after  the 
decay  is  removed,  and  that  portion  solid,  it  is  worth  an  effort  to  save. 

When  these  cases  present  themselves  for  consideration  my  first  step  is  to  remove 
all  decay  as  nearly  as  possible.  This  will  generally  cause  hemorrhage  from  the 
wounded  gum,  which  is  stopped  with  adrenalin.  The  end  of  the  root  is  thoroughly 
dried,  and  the  canal  or  canals  treated  with  formocrescl.  A  piece  of  temporary  stopping 
of  sufficient  size  to  fill  the  cavity  (in  gum)  is  thoroughl}'  softened  and  made  into  a 
cone,  or  other  appropriate  shape,  and  forced  in  place  so  as  to  move  the  gum  tissue 
out.  The  patient  is  dismissed  to  return  a  day  or  two  later,  and  at  the  next  sitting 
all  decay  is  thoroughly  removed,  the  canal  cleansed  and  again  treated  with  formo- 
cresol,  and  the  cavity  packed  as  before.  The  patient  is  dismissed  for  five  or  six  days 
and  on  returning  the  canals  are  sealed  at  the  apex,  if  they  are  in  proper  condition; 
if  not,  this  is  done  at  a  later  sitting.  The  end  of  the  root  will  generally  be  well 
defined,  and  you  are  now  ready  to  begin  the  restoration. 

If  the  root  is  an  anterior  one  an  all-porcelain  crown  with  attached  jiin  is  selected 
that  is  long  enough  to  allow  the  porcelain  to  extend  beyond  the  gum  margin,  thus 
avoiding  the  possibility  of  a  dark  joint  at  the  gum  line.  The  pin  is  ground  to  proper 
length,  and  inlay  wax  that  has  sufficient  rigidity  to  stand  carving  is  chosen.  (I 
personally  prefer  the  Standard,  put  up  by  The  Ransom &;  Randolph  Co.)  A  sufficient 
quantity  of  this  is  softened  and  placed  around  the  base  of  the  pin,  so  as  to  leave  an 
excess.  While  the  wax  is  fairly  soft  the  crown  is  pressed  into  place  and  held  firmh- 
until  the  wax  is  hard.  Crown  and  wax  are  now  removed,  the  wax  is  trimmed  to  the 
size  of  the  root  and  crown,  the  piece  is  again  put  in  place  to  ascertain  if  the  adaptation 
is  perfect.    A  sprue  wire  is  attached  and  the  case  is  invested  as  directed  for  casting 


104  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

acolite.  That  process  I  will  not  describe  here  as  it  would  be  taking  unnecessary 
time.  After  casting,  the  metal  is  polished  and  the  work  tried  in  to  ascertain  if  the 
adaption  is  now  perfect.  If  it  is,  the  piece  is  set  with  cement,  care  being  used  to  have 
as  little  excess  cement  as  possible,  as  it  is  more  or  less  difficult  to  remove  excess 
from  under  the  gum  and  any  left  would  act  as  an  irritant. 

If  the  root  is  a  molar,  and  you  wish  to  use  a  gold  shell  crown  as  an  abutment 
for  a  bridge,  pins  are  arranged  parallel  to  each  other  in  the  enlarged  canals.  A 
large  piece  of  wax  is  softened  and  pressed  up  on  pins,  and  allowed  to  harden.  Wax 
and  pins  are  now  removed,  the  wax  is  trimmed  to  the  size  of  the  root  as  shown  by 
the  impress.  If  the  wax  does  not  extend  sufficiently  above  the  cervical  line,  more 
wax  is  softened  and  shaped  on  the  end  of  the  piece  already  in  hand.  The  piece  is 
now  invested  and  cast.  By  this  method  we  have  supplied  a  stump  to  which  a  gold 
shell  crown  is  easily  adjusted. 

I  have  suggested  the  use  of  acolite  in  the  restoration  of  these  roots  because  it 
can  be  done  at  a  much  smaller  cost  to  the  patient  than  would  be  possible  if  gold  was 
used,  and  at  the  same  time  done  well. 

Where  molars  are  too  badly  decayed  to  fill  with  amalgam  and  on  account  of 
cost  the  patient  cannot  have  gold  inlays,  this  same  method  may  be  used  to  make 
acolite  inlays  that  will  give  comfortable  service. 


CAST   ANTERIOR    BRIDGE   ABUTMENTS    AND    VARIATIONS    OF   THE 
SAME  FOR  PERMANENT  SPLINTING  OF  LOOSE  TEETH 

By  George  C.   McCann,  D.D.S.,   Danville,   111. 

Doctor  McCann's  table  clinic  demonstrated  the  technique  and  use  of  two 
anterior  bridge  abutments  —  one  consisting  of  a  root  canal  dowel,  with  lingual  and 
proximal  gold  backing  attached.  The  enamel  of  the  tooth  (preferably  six  anterior) 
being  ground  so  as  to  accommodate  the  occlusion  with  sufficient  thickness  of  gold. 
The  margins  of  the  backing  carried  to  self-cleansing  areas.  The  other  consisted  of 
an  anterior  attachment  for  a  live  tooth  (preferably  bicuspids).  Trimming  the  lingual, 
occlusal  and  proximal  surfaces  to  accommodate  thickness  of  gold  and  to  self-cleansing 
areas.  A  groove  is  then  produced  with  a  millimeter  cross  cut  fissure  bur  over  the 
proximal  and  occlusal  surfaces. 

Splints  for  loose  anterior  teeth  were  modifications  of  the  abutments.  For  the 
lower  anterior,  axial  directed  pits,  1.5  to  2  m.  m.  in  depth  were  made  on  the  lingual. 
Into  the  pits  stub  pins  were  placed  and  a  casting  made  supporting  pins  and  furnish- 
ing a  solid  lingual  backing  to  the  teeth;  a  splint  was  then  soldered  to  either  form  of 
bridge  abutments  placed  on  sound  teeth. 

A  posterior  splint  consisted  of  a  wire  placed  in  an  occlusal  groove  of  loose  teeth 
and  supported  by  inlays  located  in  sound  abutting  teeth  at  each  end. 

The  purpose  of  the  clinic  was  to  present  strong  esthetic  abutment  of  anterior 
work  by  confining  the  case  to  the  lingual  aspect. 


ANCHOR  FOR  FILLINGS  AND  INLAYS 

By  W.   H.   Pelton,  D.D.S.,   Fostoria,  Ohio. 

Every  dentist  has  experienced  the  difficulty  of  anchoring  large  fillings  and 
inlays,  particularly  in  approximal  cavities,  where  the  gingival  and  incisal  portions 
are  involved  in  the  cavity.  The  failure  of  such  fillings  is  due  to  the  fact  that  we 
depend  upon  frail  enamel  and  cement  to  anchor  the  filling  or  inlay.  Naturally, 
these  elements  have  a  lesser  resistance  than  the  filling  or  inlay. 

The  anchoring  device  I  here  present  is  so  fashioned  that  it  forms  an  inter- 
locking union  of  metal  with  the  tooth  and  filling  that  has  as  great  a  resistance  as  the 
tooth  or  filling.  With  the  anchor  you  depend  on  a  22  gauge  18k.  gold  post  set  in 
the  sound  dentine  to  anchor  the  filling  or  inlay  at  the' incisal  edge  and  at  the  gingival 
portion  one  end  of  the  anchor  is  set  in  the  sound  dentine.  The  anchor  post  is  bent 
at  a  right  angle  and  interlocks  with  the  anchor,  forming  a  po.sitive  lock  of  gold  with 
the  tooth  and  filling  or  inlay. 

We  will  consider  first  the  preparation  of  a  cavity  in  a  central  for  a  gold  filling, 
it  being  unnecessary  to  devitalize.  After  removing  decay,  take  sandpaper  disc  and 
cut  the  labial  and  lingual  enamel  parallel  with  the  long  axis  of  the  tooth,  then  with  a 
carborundum  stone  cut  a  flat  gingival  seat.     Bevel  the  labial  and  lingual  enamel 


Fig.  1 


Fig.  2 


according  to  your  own  idea  and  build  up  the  pulpal  floor  with  cement  until  it  is  flush 
with  the  labial  and  lingual  enamel,  leaving  no  undercuts  or  concave  surfaces.  Drill 
a  hole  (Fig.  1)  in  the  gingival  seat  to  receive  one  end  of  the  anchor  and  drill  a  hole  in 
the  pulpal  wall  near  the  incisal  edge  at  an  acute  angle  with  the  pulpal  wall.  Place 
one  end  of  the  anchor  in  the  gingival  pit  and  pass  the  anchor  post  through  the  hole 
in  the  anchor  and  into  the  hole  in  the  pulpal  wall  previously  filled  with  cement. 
The  anchor  is  so  formed  that  flanges  are  bent  at  a  right  angle  and  extend  labially 
and  lingually.  The  gold  is  condensed  between  the  pulpal  wall  and  the  flanges, 
and  as  the  filling  is  built  up  each  portion  of  gold  is  interlocked  with  the  anchor. 
Non-cohesive  gold  can  be  used  in  the  first  two-thirds  and  cohesive  in  the  remaining. 
This  anchor  is  indicated  in  bicuspids  and  molars  where  large  cavities  are  restored 
with  amalgam.  It  is  unnecessary  to  involve  the  enamel  in  the  retention  of  the  filling 
— the  anchor  will  resist  the  stress  and  retain  the  filling. 

The  casting  machine  creal;ed  the  greatest  enthusiasm  among  the  dentists,  yet 
many  a  man  has  to  regret  that  the  cast  inlay  has  been  cxpensi\c  to  his  practice, 


106  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

yet  the  failure  of  gold  inlay  in  large  restoration  is  due  to  the  cement  not  being  strong 
enough  to  resist  the  stress.  The  anchor  enables  us  to  go  one  step  forward,  which 
gives  us  an  inlay  with  a  mechanical  retaining  device.  The  cavity  for  inlays  is  pre- 
pared similar  to  the  cavity  in  Fig.  1. 

We  will  now  consider  an  inlay  in  a  central   (Fig.  2). 

Cement  the  pulpal  floor  flush  with  the  labial  and  lingual  walls,  leaving  no  under- 
cuts; drill  a  hole  in  the  gingival  seat  with  a  round  bur,  to  receive  one  end  of  the  anchor; 
then  drill  a  hole  near  the  incisal  edge  for  the  post;  now  cement  the  post  to  place 
with  the  right  angle  part  parallel  with  the  long  axis  of  the  tooth  and  pointing  toward 
the  incisal  edge.  Continuing,  place  the  tube  part  (Fig.  2)  of  the  anchor  in  position 
in  the  cavity — seeing  that  the  full  round  part  of  the  tube  interlocks  with  the  post, 
then  adapt  the  inlay  wax  and  carve  the  wax  to  conform  with  the  tooth.  Now  remove 
the  wax  model  by  pulling  it  straight  away  from  the  cavity  (there  being  no  undercuts 
the  wax  will  come  away  without  being  distorted).  The  tube  part  of  the  anchor 
will  come  away  with  the  wax.  Invest  the  wax  model  with  the  tube  part  of  anchor 
in  place  just  as  it  is  taken  from  the  cavity.  The  tube  must  be  filled  with  the  invest- 
ment (using  a  camel's  hair  brush).  When  you  cast,  the  gold  will  fuse  to  the  anchor, 
making  the  anchor  and  inlay  in  one  piece. 


Fig.  3 

In  using  the  inlay  anchor  in  the  construction  of  bridge  work  (Fig.  3)  the  cavity 
is  prepared  similar  to  inlay  in  Fig.  2.  The  anchors  are  placed  in  position  and  the 
cavities  built  up  with  the  inlay  wax;  a  suitable  facing  is  then  attached  to  the  wax 
in  the  cavities,  then  the  wax  model  is  removed  and  invested  as  in  Fig.  2  and  cast. 
This  will  give  you  a  beautiful  piece  of  work  that  is  sanitary  and  is  constructed  with 
less  sacrifice  of  tooth  substance  than  by  any  other  known  method. 


CAST  POSTS  FOR  STEELE'S  FACING 

By  George  H.  Walker,  Los  Angeles,  Cal. 

This  is  a  portion  of  a  gold  rib  cast.  One  end  is  cut  and  shaped  for  the  anterior 
teeth  and  the  other  for  posterior.  Wax  is  forced  about  the  rib  when  in  tooth  and 
shaped  to  suit.  Facing  then  removed  and  the  wax  invested  and  a  casting  made  as 
per  finished  tooth. 

A  sheet  of  base-plate  wax  is  placed  on  a  flat  surface  at  the  edge,  and,  beginning 
with  the  largest  hole,  the  draw  plate  is  drawn  over  the  edge  of  wax,  gradually  cutting 
wax  down  to  size  of  smallest  hole.  Wax  is  then  cut  from  sheet,  forming  strips, 
as  per  sample — a  sprue  attached  to  one  end — coiled  like  watch  spring,  flasked  and 
cast.     Wax  must  be  chilled  to  draw  nicely. 


METHODS  OF  CASTING  IN  CROWN  AND  BRIDGE  WORK 

Dy  W.   G.  Crandall.   D.D.S.,  Spencer,   Iowa. 

ALL   CAST   CROWN 

It  is  posLible  to  cast  an  entire  gold  crown,  and  it  is  at  times  practical.  It  makes 
a  piece  of  work  that  is  heavy,  expensive  and  difficult  to  handle. 

It  is  always  necessary  to  have  a  tooth  perfectly  trimmed  of  all  enamel  before 
starting  to  make  a  crown.  It  is  absolutely  essential  that  there  be  no  overhanging 
wall  of  dentine. 

If  the  tooth  has  one  or  more  walls  of  dentine,  build  it  up  with  amalgam  so  that 
the  walls  slightly  converge  toward  the  occlusal.  Next  give  the  surface  a  finish  with 
strips  or  discs.  The  casting  wax  may  be  applied  directly  over  the  prepared  tooth  if 
the  operator  is  skillful  enough  to  carve  and  finish  while  in  position.  This  is  not  an 
easy  thing  to  do  unless  the  gum  has  previously  been  forced  out  of  the  way  to  give 
access  for  convenient  finishing  about  the  root. 

The  easier  way  is  to  take  an  impression  with  gutta  percha,  metalline,  modelling 
compound  or  cement.  With  a  burnisher  work  the  impression  material  close  about 
the  root,  being  sure  that  the  impression  is  perfect.  Do  not  allow  the  impression  to 
interfere  with  occlusion.  When  the  impression  material  is  thoroughly  hardened  take 
the  bite  with  modelling  compound  or  wax,  bringing  away  the  root  impression  in 
position  in  the  bite  material. 


Fig.  la  Fig.  lb 

The  roct  impression  should  be  coated  with  some  separating  material  and  then 
filled  up  with  cement;  either  build  down  quite  long  or  rough  so  that  it  will  be  held 
firmly  in  the  plaster  model  or  insert  metal  pins  for  that  purpose. 

The  case  is  now  ready  to  place  in  crown  articulator  and  pour  up  with  plaster. 

When  hard,  remove  the  bite  and  impression  and  you  have  an  exact  reproduction 
of  the  tooth,  approximating  teeth,  occlusion  and  surrounding  parts. 

Either  wet  or  oil  the  model,  then  proceed  to  melt  on  the  casting  wax  a  few  drops 
at  a  time  and  carve  to  form.  It  is  possible  to  give  form  to  a  crown  in  this  manner 
that  it  would  be  very  difficult  or  impossible  to  form  with  contouring  pliers.  A  fit 
beneath  the  gum  line  may  be  made  as  perfect  as  that  of  any  inlay  and  this  is  more  than 
can  be  said  for  most  gold  crowns. 

A  most  perfect  fit  at  the  gingival  line  may  be  made  by  cutting  a  seat  at  right 
angles  to  the  long  axis  cf  the  root  upon  the  mesial  and  distal  surfaces  just  beneath 
the  free  margin  of  the  gum  (Fig.  1)  and  finishing  the  crown  flush  with  this  line. 

The  possibilities  of  the  contacts  and  contours  are  limited  only  by  the  variety 
of  cases  and  the  skill  of  the  operator. 


108 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


CAST   CUSPS 

In  making  cast  cusps  for  a  crown  the  band  should  be  made  in  the  usual  manner, 
paying  very  little  attention  to  contour.  Take  bite  or  impression  in  the  usual 
manner  and  place  on  the  articulator.  A  thin  film  of  wax  within  the  band  at  the 
gingival  portion  will  facilitate  its  removal  when  upon  the  model. 

The  root  model  may  be  built  down  with  plaster  so  as  not  to  leave  room  for  too 
great  a  thickness  of  casting  wax  and  a  subsequent  thickness  of  gold.  The  wax  can 
be  melted  over  the  surfaces  of  the  band,  giving  buccal,  lingual  and  approximal 
contour  with  precision.     The  occlusion  can  be  tried  and  carved  to  an  exactness. 

The  waxed  up  model  of  either  variety  of  crown  should  be  thoroughly  trimmed 
and  smoothed  (gasoline  or  chloroform  is  good  for  this  purpose)  so  that  none  of  the 
contour  need  be  filed  or  polished  away. 


Fig.  2 

The  sprue  wire  should  be  inserted  into  the  wax  of  the  occlusal  portion  within 
the  crown  (Fig.  2).     This  is  important  when  casting  upon  bands,  as  will  be  seen  later. 

In  investing  these  crowns  they  should  be  placed  as  near  the  surface  of  the  in- 
vestment as  the  strength  of  the  investment  will  allow.  It  must  be  remembered 
that  the  occlusal  surface  of  most  crowns  is  quite  a  large  surface  and  there  must  be 
sufficient  investment  material  to  warrant  a  resistance  to  the  molten  gold  when  it  is 
thrown  against  it.  It  has  been  my  experience  that  a  depth  of  from  3  to  5  m.  m. 
should  be  allowed  for  sufficient  strength. 

After  the  investment  material  has  become  sufficiently  hard  (15  to  30  minutes 
will  suffice  for  most  investments)  the  sprue  wire  should  be  removed  and  the  case 
inverted  over  a  flame  that  will  melt  and  burn  out  the  casting  wax.  When  the  in- 
vestment becomes  red  with  the  heat  it  should  be  inverted  and  heated  until  the 
investment  can  be  seen  to  be  at  a  white  heat  through  the  sprue  hole.  This  is  im- 
portant, for  the  gold  will  not  fuse  to  the  band  unless  it  is  well  heated.  A  failure  will 
be  unknown  if  the  case  is  thoroughly  heated  and  properly  cast. 

If  a  taper  pointed  sprue  has  been  used,  the  crown  when  cast  can  be  easily 
separated  from  the  cast  sprue  by  twisting  in  the  fingers.  A  separation  can  be  had 
at  just  the  right  point  if  care  has  been  used  in  placing  the  sprue  in  the  wax  and  an 
excess  of  wax  not  allov/ed  to  adhere  to  the  sprue.  Anj-  excess  remaining  can  easily 
be  cut  out  with  a  bur  or  small  stone. 

A  crown  made  after  this  method  will  need  very  little  polishing  to  produce  a 
beautiful  result,  providing  care  Was  been  taken  in  every  step. 

The  Richmond  Crown  is  practical  upon  any  of  the  teeth  that  will  admit  of  a 
sufficient  length  for  the  porcelain  facing. 


METIIODS  OF  CASTING  IN  CROWN  AND  liRIDCE  WORK 


101) 


liKIDCiK     WdKK 

\Vl'  will  suppise  thai  thi;  l^oKI  cruwii  we  ha\x'  just  cast  is  for  the  upper  left  first 
molar,  the  two  bicuspids  are  missing,  the  bite  is  very  clcse  and  we  want  to  place  a 
Richmond  crown  upon  the  left  cuspid  and  bridge  the  space. 

Before  making  our  Richmond  crown  we  will  trim  the  root  a  little  differently 
than  the  usual  custom.  The  labial  half  of  the  root  end  is  beveled  beneath  the  gum 
line  with  a  root  facier  and  stone  as  for  a  Lcgan  crown.  The  lingual  half  of  the  root 
end  will  not  be  beveled  nor  cut  down  to  the  gum  line,  but  will  be  cut  flat,  making  a 
good  seat  for  the  crown.  The  enamel  should  now  be  thoroughly  remo\ed  from  the 
root  (Fig.  3). 

An  iridio-platinum  wire  ai)out  16  gauge  is  fitted  to  the  canal  and  left  protruding 
from  the  root  end  about  2  m.  m.  A  suitable  facing  is  ground  to  position,  allowing 
room  for  a  gold  tip  for  the  protection  of  the  facing.  The  pins  should  be  bent  so  as 
not  to  interfere  with  occlusion  or  the  contour  of  the  crown. 

A  piece  of  casting  wax  of  sufficient  si.'.e  should  now  be  scftened,  or  better,  melted 
upon  the  back  cf  the  facing,  approximating  the  shape  of  a  crown,  and  the  root  pin 
inserted.     This,  while  soft,  should  be  forced  upon  the  root,  the  facing  adjusted  to 


the  desired  position  and  occlusion  carefully  noted.  The  wax  should  be  tightly 
burnished  about  the  root  with  cold  burnisher.  After  thorough  adjustment,  chill 
anil  remove  for  careful  trimming.  Casting  wax  that  is  sufificicnth'  hard  to  admit  of 
handling  and  trying  in  che  mouth  without  danger  of  changing  form,  should  be  used. 
When  the  desired  form  is  secured  and  the  wax  smoothed  the  sprue  wire  should  be 
inserted  in  the  wax  upon  the  lingual  surface  of  the  crow-n  at  right  angles  to  the  back 
of  the  facing. 

Great  care  should  be  taken  that  no  wax  extends  over  the  labial,  mesial  or  distal 
surfaces  of  the  facing  as  this  would  be  liable  to  cause  a  check  in  casting. 

This  arrangement  places  the  facing  in  the  position  to  receive  the  most  possible 
heat  in  the  investment.  The  investment  should  be  made  the  same  as  for  the  gold 
crown,  the  wax  melted  out,  the  case  inverted  and  heated  slow  !>•  at    first.  gradualK' 


no  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

increasing  the  heat  to  the  extreme,  so  that  when  the  hot  gold  is  cast  upon  the  facing 
there  will  not  be  enough  difference  in  temperature  to  cause  sufficient  expansion  to 
check  the  facing. 

The  moment  the  cast  is  made  and  the  gold  has  hardened  the  case  should  be 
covered  with  dry  plaster  and  left  until  thoroughly  cool.  Most  of  the  failures  in 
casting  onto  facings  have  been  due  to  rapid  cooling.  Powdered  plaster  will  keep 
the  case  warm  for  about  a  half  hour  or  more  and  it  is  time  saved  to  leave  it  plenty 
long  enough. 

A  crown  made  carefully  after  this  method  should  go  to  place  on  the  root  as  per- 
fectly as  any  inlay  and  if  properly  finished  should  never  become  an  irritant  to  the 
gum  tissue. 

To  complete  our  bridge  we  will  place  the  crowns  in  position  and  take  accurate 
bite  and  impression.  This  is  easily  done  with  plaster  on  the  Detroit  bite  impression 
tray,  bringing  the  crowns  away  in  position  and  allowing  no  chance  for  change  of  bite. 

The  inside  of  the  crowns  should  be  coated  with  a  thin  film  of  wax  and  the  case 
mounted  in  plaster  on  the  articulator.  Separate  and  warm  crowns  sufficiently  to 
melt  wax  and  thoroughly  clean  out  all  wax  so  that  crowns  rest  perfectly  in  position. 

Bicuspid  facings  are  now  ground  and  fitted,  casting  wax  applied  to  them,  and 
while  warm  they  are  placed  in  position  and  the  articulator  closed  and  worked  about 
as  in  chewing.  Now  carve  cusps  and  trim  wax  as  you  want  the  bridge  when  finished. 
Use  great  care  that  wax  does  not  overlap  the  facings  in  any  position.  It  should  cover 
the  same  portion  of  the  facing  as  you  would  include  in  backing  a  tooth  for  soldering. 
The  case  should  be  invested  and  cast  the  same  as  the  cuspid  crown.  It  is  now  ready 
for  assembling.  This  is  not  done  in  any  way  different  from  the  ordinary  procedure, 
with  the  exception  that  very  little  solder  is  necessary. 

This  makes  a  bridge  that  is  nearly  perfect  hygienically.  There  is  no  space 
between  the  facing  and  gold  as  with  ordinary  backing,  there  are  no  solder  pits  to 
cause  trouble  in  finishing.  The  crowns  fit  like  inlays,  allowing  a  minimum  of  cement 
which  we  all  know  is  the  foulest  of  substances  when  removed  from  an  old  crown. 

The  color  of  the  gold  should  be  uniform,  the  same  kind  of  gold  being  used 
throughout. 

In  casting  anterior  cases  where  it  is  desirable  to  have  the  case  thin  linguo- 
labially,  I  would  suggest  clasp  metal.  Though  difficult  to  melt  sufficiently  to  cast, 
it  gives  the  maximum  of  strength  and  rigidity  for  its  bulk. 

If  it  is  desirable  to  have  the  facings  removable,  the  backs  of  the  facings  should 
be  oiled  and  the  pins  left  straight.  After  the  waxing  up  has  been  completed,  remove 
facings  and  place  sharpened  pencil  points  in  the  pin  holes,  having  the  points  long 
enough  for  the  investment  to  hold  in  position  for  casting.  Facings  can  be  easily  ad- 
justed and  cemented  to  position  after  bridge  is  completed. 

Another  good  method  for  making  facings  removable  and  a  strong  attachment 
when  in  position,  is  done  by  bending  the  pins  down  on  the  facing  so  they  lap,  and  as 
close  together  as  possible.  Then  cover  with  soft  solder  or  some  of  the  easily  fusible 
metals.  Grind  this  into  a  box  form  just  so  that  it  can  be  withdrawn  from  wax 
without  pulling.  This  makes  a  very  strong  attachment  and  is  easily  and  quickly 
made. 


AN  IDEAL  BICUSPID  OR  MOLAR  CROWN 

By  George  S.  Schlegel,  D.D.S.,  Reading,  Pa. 

An  ideal  artificial  crown  is  one  that  possesses  all  the  qualifications  of  its  natural 
predecessor.  In  fact,  the  artificial  substitute  cannot  decay,  can  be  easily  repaired 
if  broken,  and  very  often  makes  a  better  appearance  than  the  natural  tooth,  when 
the  latter  is  affected  with  atrophy  of  the  enamel,  discolorations,  and  partial  fractures. 
In  order  that  I  be  not  misunderstood,  I  wish  to  inform  my  readers  that  a  tooth  should 
not  be  crowned  unless  it  cannot  possibly  be  repaired  with  some  permanent  filling 
material  suited  to  the  class  and  position  of  cavity  or  cavities. 

The  crown  I  wish  to  describe  is  made  possible  by  the  application  of  the  principle 
of  casting  gold  under  pressure.  The  method  can  be  used  for  any  tooth  in  the  mouth, 
but  is  especially  adapted  for  bicuspids  and  molars.  No  ethical  dentist  should  place 
a  gold  crown  on  the  oral  teeth,  but  bicuspids  and  molars  are  crowned  by  them, 
with  the  hollow  shell  crown,  because  the  repertoire  of  crowns  used  to  date  lacked 
one  that  possessed  both  the  necessary  strength  and  esthetic  qualities.  I  will  point 
out  the  value  of  this  crown  to  others  now  commonly  used  by  comparison  at  the  con- 
clusion of  this  article. 

In  order  to  give  you  a  clear  conception  of  this  method,  I  will  describe  how  to 
make  a  superior  first  bicuspid  crown: 

The  proper  preparation  of  the  root  is  essential  for  the  proper  adaptation  of 
the  crown  as  for  any  other  crown.  The  root  should  be  filled  with  red  gutta  percha 
points,  which  serve  as  a  guide  in  reaming  the  root  canals,  the  little  red  spot  indicating 
the  direction  of  the  root.  The  diameter  of  the  canals  should  be  enlarged  in  propor- 
tion to  the  diameter  of  the  root.  I  use  No.  16  to  20  gauge  iridio-platinum  wire  in 
the  roots. 

The  next  step  is  to  cut  down  the  root  flush  with  the  gum  line.  Then  bevel  root 
on  the  buccal  side,  and  palatal  side  to  about  one  m.  m.  below  the  free  margin  of  the 
gum.  Take  a  No.  5  or  6  bur  to  countersink  opening  to  the  reamed  root  canal  to 
the  depth  of  IJ^  m.  m.  I  insert  iridio-platinum  wire  into  each  canal,  cut  flush  with 
surface  of  root,  and  remove  to  bracket  table  for  future  use.  This  completes  the  root 
pre]:)a  ration. 

The  next  step  is  the  selection  of  a  porcelain  detachable  crown  of  any  make 
desired,  but  of  such  a  size  and  color  that  will  conform  to  the  case.  If  necessary 
to  grind  to  occlusion,  grind  the  occlusal  surface;  the  reasons  for  this  I  will  point  out 
later. 

Now  take  a  piece  of  black  inlay  wax  of  a  rather  stiff  quality,  like  S.  S.  White's, 
and  after  lubricating  the  inside  of  the  opening  of  the  artificial  crown  with  a  little 
sweet  oil  or  glycerin,  press  the  wax,  which  was  previously  warmed,  into  the  opening 
of  the  tooth.  Withdraw^  to  see  if  the  undercuts  in  the  tooth  interfere  with  proper 
removal,  and  if  they  do,  correct  the  fault.  Return  wax  to  crown,  and  trim  approxi- 
mately. Warm  slightly  and  press  crown  with  wax  to  the  root.  Note  the  condition 
of  occlusion,  position  in  arch,  etc.,  then  chill  with  iced  water  and  remove.  Note 
the  opening  to  the  canals  by  the  elevation  in  the  wax.  Heat  the  iridio-platinum 
pins  previously  fitted  in  the  roots,  and  place  in  approximal  position  in  wax.     Return 


112  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

to  root  for  final  adjustment.  Be  sure  that  all  the  wax  is  hidden  beneath  the  gum. 
Chill  again,  remove  carefully  from  root,  then  remove  wax  from  the  crown.  Care- 
fully insert  a  sprue  wire  at  the  end  of  the  wax  with  pins,  which  touches  the  remotest 
part  of  the  opening  in  the  artificial  crown.  Invest  and  cast  according  to  any  of  the 
methods  used  in  casting  gold  inlays.  Cement  crown  on  cast  base,  and  then  cement 
the  crown  and  base  to  place. 

This  gives  you  a  crown  that  is  perfectly  adapted,  esthetic,  durable  and  easy  to 
repair.  The  reason  for  grinding  the  occlusal  surface  is  obvious  from  the  fact  that 
repairs  would  be  easier  if  a  record  is  kept  of  the  number  of  the  mold  used,  then  a 
tooth  of  the  same  mold  will  fit  the  case  without  any  grinding  at  the  gum  line. 

It  is  my  firm  conviction,  gained  from  actual  experience  with  the  insertion  of 
these  crowns  for  a  period  of  over  a  year,  that  they  are  ideal.  They  are  better  than 
a  gold  crown  for  esthetic  reasons.  Better  than  a  Richmond  crown  because  in  this 
ideal  crown  no  band  is  needed,  for  bands  are  an  abomination  at  best,  and  unless  a 
Steele's  Detachable  Facing  is  used,  the  color  is  often  far  from  satisfactory.  Again, 
gold  tips  are  unsightly.  Better  than  a  Logan  crown  because  it  is  very  often  difficult 
to  adapt  to  the  root.  Again,  the  leverage  on  the  pins  is  very  great,  and  often  ends 
in  the  splitting  of  the  roots.  Better  than  a  porcelain  or  platinum  jacket  crown, 
because  either  is  liable  to  fracture,  and  difficult  to  repair. 


CAST  ABUTMENTS  FOR  THE  ATTACHMENT  OF  BRIDGES 

By  W.   M.   McCall,  D.D.S.,  Louisville,   Ky. 

Cast  abutments  for  the  attachment  of  bridges,  using  in  this  case,  superior  left 
cuspid  to  first  molar. 

Prepare  the  cuspid,  first  by  removing  with  the  stone  sufficient  amount  of  tooth 
structure  from  lingual  portion  of  tooth  to  give  room  for  construction  of  inlay.  Grind 
two  small  grooves  across  lingual  surface,  then  with  small  round  bur  make  three 
openings,  two  towards  incisal,  one  towards  gingival.  In  grooves  which  were  made 
in  tooth,  fit  number  twenty  (20)  platinum  wire  and  proceed  to  construct  the  inlay  in 
the  usual  manner. 

To  prepare  the  molar  tooth,  grind  off  occlusal  surface,  starting  at  lingual  and 
gradually  tapering  towards  buccal  surface.  Then  cut  cavity  in  mesial  portions, 
extending  under  free  margin  of  gum,  and  from  lingual  to  buccal  of  mesial  surface, 
placing  in  the  occlusal  two  or  three  number  twenty  (20)  platinum  pins,  so  as  not  to 
come  in  contact  with  the  pulp  of  the  tooth.  Proceed  to  construct  inlay  in  the  usual 
manner.  Place  inlays  in  position,  take  bite  and  impression,  using  for  dummies 
Brewster's  diatoric  teeth.  Grind  up  dummies,  swage  backing  and  solder  as  in  ordi- 
nary piece  of  bridge  work.  A  bridge  properly  constructed  and  attached  by  this 
method  is  very  ?trong  and  durable.  The  main  feature  is  that  no  gold  shows  on  labial 
and  buccal  surface. 


THE  SCOPE  OF  CASTING  IN  DENTISTRY 

By  R.  C.   Brophy,   M.D.,  D.D.S.,   Chicago,   III. 

While  casting  metals  in  dentistry  is  by  no  means  of  strictly  modern  origin,  it 
is  only  of  late,  or  following  the  announcement  of  the  application  of  the  principle 
to  operative  work  by  Dr.  Wm.  H.  Taggart,  that  it  has  come  to  be  regarded  with 
particular  interest  by  the  profession.  It  is  doubtful,  however,  if,  with  all  the  interest 
shown  at  the  present  time,  the  complete  scope  of  the  work,  or  full  field  in  which  it  is 
applicable,  is  properly  appreciated. 

It  is  not  the  purpose  of  the  writer  to  dwell  upon  the  casting  of  inlays  proper,  as 
substitutes  for  fillings,  for  that  subject  is  being  widely  discussed,  and  is  quite  well 
understood,  but  I  would,  taking  that  as  a  starting  point  in  consideration  of  my 
subject,  follow  along  further  and  take  up  other  things  in  the  same  field. 

I  have  always  felt  that  there  are  possibilities  in  the  process  of  casting  in  den- 
tistry of  really  greater  value  and  importance  than  the  casting  of  inlays  to  fill  cavities 
in  the  crowns  of  teeth. 

Making  use  of  inlays  is  dependent  upon  the  extent  to  which  destruction  of  the 
crown  of  a  tooth  has  been  allowed  to  proceed;  their  applicability  must  be  measured 
by  the  proportion  of  the  crown  remaining;  there  must  be  a  given  area  of  sound, 
solid  tooth  structure  to  support  them.  Many  cases  present  where  there  is  not  such 
sufficient  sound  structure,  and  it  is  in  such  instances,  in  the  writer's  opinion,  that 
there  lies  the  greater  possibilities  of  valuable  accomplishments  through  the  casting 
process. 

It  is  a  pity  that  teeth  are  allowed  to  pass  beyond  the  pale  of  repair  by  simply 
plugging  cavities;  but  the  time  will  never  come  when  the  dentist  will  not  meet  con- 
ditions either  presaging  the  complete  loss  of  the  tooth,  or,  exacting  extreme  ingenuity 
and  skill  in  its  saving.  It  is  not  so  much  a  question  as  to  whether  the  dental  pro- 
fession could  keep  everybody's  teeth  in  normal  condition,  and  intact,  as  it  is  a  fact 
that  it  never  will  have  an  opportunity  to  do  anything  of  the  kind.  People  sometimes 
neglect  to  lock  the  barn  door  until  after  the  horse  is  stolen.  A  great  many  people 
never  entertain  a  thought  of  consulting  the  dentist  until  their  teeth  are  so  extensively 
involved  in  destruction  that  artificial  restitution  is  demanded. 

Then,  again,  the  matter  of  casting  inlays  proper  applies  only  to  those  cases 
where  restoration  of  a  tooth  may  be  accomplished  by  old,  ordinary  methods  of 
operative  procedure.  I  want  to  connect  the  casting  process  with  those  cases  which 
no  dentist  would  think  for  a  moment  of  attempting  to  restore  by  operative  procedure, 
those  cases  in  which  the  little  remaining  structure,  merely  the  shell  of  a  root,  though 
it  be,  are  made  use  of  as  an  abutment  or  anchorage  for  a  cast  restoration,  or  the 
mounting  thereon  of  a  porcelain  crown. 

It  is  scarcely  possible  to  conceive  of  a  tooth  assuming  a  condition  of  deca> , 
which,  from  a  mechanical  standpoint  cannot  be  restored,  if  the  casting  process  be 
employed,  waiving,  however,  discussion  of  the  many  things  that  may  be  done  in  the 
way  of  restoration  of  the  crown  of  a  tooth  where  the  root  is  sound  and  solid.  I 
would  speak  particularly  of   that  procedure  which   I   believe  constitutes  the  most 


114  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

valuable  and  important  achievement  possible  in  casting.  I  refer  to  the  mounting 
of  crowns  upon  badly  decayed  roots  where,  possibly,  but  a  shell  remains,  and  this 
shell  buried  beneath  the  margin  of  the  gum. 

The  method  of  making  such  a  restoration  is  so  simple  that  it  can  but  appeal  to 
all.  If  the  shell  upon  which  it  is  desired  to  mount  a  crown  be  deep  down  underneath 
the  gum,  it  will  be  found  that  gum  tissue  has  covered,  and  likely,  partially  filled  it, 
and  in  that  case  this  tissue  must  be  crowded  back  by  packing.  The  root  should  then 
be  cleaned  of  all  debris  and  its  edge  trimmed  to  a  solid  margin. 

If  the  restoration  is  to  be  made  of  gold,  a  detachable  pin  crown  should  be  used, 
the  dowel,  or  pin,  with  the  crown  in  position  upon  it,  should  be  invested  with  softened 
inlay  wax  and  should  be  crowded  down  into  the  root,  the  latter  having  first  been 
moistened  with  saliva.  This  procedure  should  give  a  perfect  model  of  the  canal, 
or  shell,  and  a  perfect  mold  of  the  base  of  the  porcelain  crown.  The  crown  may 
now  be  taken  off  the  dowel,  and  the  latter,  with  the  wax  model  attached  to  it,  may 
be  lifted  out,  trimmed,  reset,  removed  again  and  retrimmed,  until  finally  the  wax  is 
found  to  be  perfectly  adapted.  The  crown  should  then  be  removed,  the  sprue  wire 
attached,  and  the  case  is  ready  for  investing  and  casting. 

If,  instead  of  making  the  restoration  with  gold,  Acolite  be  used — and  for  these 
cases  the  writer  does  not  hesitate  to  say  that  he  regards  Acolite  preferable  to  gold — 
the  cast  may  be  made  direct  to  the  porcelain,  or  not,  as  is  desired,  and  ordinary 
vulcanite  plate  teeth  and  German  silver  dowels  may  be  used  instead  of  special 
crowns  with  their  dowels.  After  the  restoration  is  finished  it  may  be  set  with 
cement,  and  if  the  crown  used  be  detachable,  it  may  then  be  cemented  in  position 
on  the  dowel. 

The  casting  process  in  relation  to  bridge  work  is  an  important  consideration, 
but  one  upon  which  I  realize  that  I  have  peculiar  views.  I  believe  that  if  porcelain 
teeth  of  a  detachable  or  removable  character  could  be  made  use  of,  and  as  a  matter 
of  fact  they  might  be,  that  casting  bridges  would  be  practical,  but  I  am  led  to 
believe  that  unless  the  bridge  be  cast  along  that  line  that  it  better  not  be  cast  at  all. 

I  have  long  felt  that  casting  gold  to  porcelain  is  too  uncertain  and  questionable 
to  be  practical  or  advisable.  It  is  true,  of  course,  that  a  piece  of  porcelain  will  now 
and  then  be  found  to  have  withstood  the  shock  and  the  effe-ts  of  the  natural  changes 
of  the  gold,  after  the  two  have  come  in  contact,  but  I  know  that  such  occurrences  are 
very  rare.  In  a  very  great  many  instances  the  porcelain  plainly  shows  checks. 
In  very  many  instances  the  porcelain  appears  to  the  naked  eye  to  be  uninjured,  but 
my  experience  has  shown  that  in  almost  all  cases  examination  under  a  magnifying 
glass  will  reveal  checks.  These  checks,  of  course,  weaken  the  porcelain  and  make 
it  unreliable  and  unworthy  of  dependence.  I  regard  the  casting  of  gold  to  porcelain 
as  impracticable. 

What  I  have  said  in  relation  to  casting  Acolite  in  crown  work  applies  to  bridge 
work.  Acolite,  owing  to  its  low  fusing  point  and  its  non-changing  qualities  in  con- 
gealing, may  be  cast  to  porcelain  without  danger  of  checking  it. 

Casting  metal  plates  in  dentistry  has  been  done  in  our  own  country  for  fifty 
years,  and  a  study  of  the  subject  from  a  standpoint  of  evolution  is  interesting.  Dr. 
James  B.  Bean,  who  was  the  first  dentist  to  experiment  in  the  work,  undoubtedly 
was  actuated  in  so  doing  by  a  desire  to  make  use  of  the  then  practically  new  metal 
— aluminum — for  base  plates.  It  is  doubtful  if  the  metal  was  procurable  at  that 
time  in  sheet  form  for  swaging.  Dr.  Bean  attempted  to  make  use  of  straight  aluminum 
without  trying  to  affect  any  change  in  it  by  alloying.     When  we  realize  that  pure 


THE  SCOPE  OF  CASTING  IN  DENTISTRY  ll5 

aluminum  is  not  produced  at  the  present  time,  we  may  imagine  the  purity  tf  the 
metal  he  used  at  that  early  time,  and,  knowing  what  we  do  cf  the  effects  produced 
by  certain  oral  secretions  upon  the  "pure"  aluminum  with  which  we  are  now 
supplied,  we  may  further  imagine  the  troubles  which  confronted  him  in  practice. 
It  is  quite  likely,  also,  that  Dr.  Bean  had  his  troubles  in  making  perfect  casts,  for 
he  depended  upon  gravity  to  inject  the  metal  into  the  matrix,  or  mold. 

Following  Dr.  Bean,  other  men  became  interested  in  casting  aluminum  plates, 
notably  Dr.  Carroll  and  Dr.  Zeller,  but  without  commenting  upon  their  experiences 
I  will  consider  the  matter  from  a  present  day  status,  and  purely  from  a  mechanical 
standpoint,  in  conformity  to  the  title  cf  my  paper. 

It  may  be  interesting  to  some  to  know  that  as  long  as  fifteen  years  ago  the 
writer,  as  well  as  other  dentists,  made  use  of  the  identical  principle  in  casting  plates 
that  is  being  employed  by  many  at  the  present  time,  in  the  so-called  inlay  casting, 
viz.,  burying  the  model,  using  a  crucible  former  and  sprues,  burning  out  the  wax 
and  forcing  the  metal  down  into  the  matrix  with  air  pressure. 

The  casting  of  plates  is  an  extremely  important  phase  of  dental  casting,  and  is 
found  at  the  present  time  to  be  following  very  closely  the  wonderful  development 
and  gain  in  popularity  of  other  forms  cf  dental  casting.  While  I  do  net  deem  it 
advisable  to  make  a  practice  cf  casting  large  full  base  plates  in  gold,  there  are  cases 
where  delicate  horseshoe  or  saddle  plates  may  be  cast  in  this  metal  to  advantage. 

In  the  casting  cf  Aerdentalloy  plates,  a  well  known  alloy  of  aluminum,  which 
has  been  proven  to  possess  characteristics  making  it  vastly  superior  to  straight 
aluminum  for  the  purpose,  the  dental  profession  has  one  cf  the  most,  if  not  the  most, 
important  of  all  the  many  advantageous  aids  resultant  from  the  process  cf  casting. 

Casting  in  dentistry  has  a  practically  unrestricted  scope,  and  its  value  to  the 
profession  and  to  humanity  cannct  be  computed. 


A  SIMPLE  METHOD  OF  CASTING  PIN  AND  COPING  FOR 
A  PORCELAIN  CROWN 

By  Paul  J.   Boyens,   Weed,   California. 

Select  a  detached  post  crown  to  fit  the  case  and  fit  it  to  the  root  in  the  usual 
manner.  Ream  the  canal  with  a  gradual  taper,  making  the  orifice  a  trifle  larger 
than  for  the  ordinary  post.  This  increase  in  the  size  of  the  cast  post  at  the  point 
of  greatest  strain  will  more  than  compensate  for  the  difference  in  strength  between 
the  cast  material  and  a  platinum  or  iridio-platinum  post.  Warm  a  small  piece  cf 
inlay  wax  and  roll  it  into  a  stick  that  will  approximately  fit  the  canal,  leaving  it  a 
little  long.  Lubricate  the  canal,  and  while  the  wax  is  still  slightly  plastic,  work  it 
gradually  into  the  canal.  Soften  the  projecting  end  with  a  few  blasts  of  warm  air 
and  warm  the  crown  and  press  it  firmly  into  place.  The  wax  squeezing  out  all 
around  will  indicate  that  an  accurate  impression  cf  the  root  has  been  secured.  Chill 
the  wax  thoroughly  and  withdraw,  then  with  a  sharp  knife  trim  off  the  surplus. 
Invest  in  soft  material  with  the  crown  downward,  the  wax  post  serving  as  a  sprue 
through  which  to  cast  the  gold.  Cast  in  the  usual  manner,  using  22k.  solder  or 
platinized-plate  gold.  Let  the  flask  cool  thoroughly  before  opening.  Various 
modifications  cf  this  method  can  be  made.  A  plate  or  a  vulcanite  tooth  may  be 
used,  in  which  case  it  is  advisable  to  leave  the  lingual  side  of  the  root  a  little  longer. 

—Denial  Brief. 


116  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

METHOD  OF  PRODUCING  PERFECT  MARGINS 

By  C.  Kabell,  Chicago,  III. 

The  practical  value  of  the  cast  filling,  its  ease  of  manipulation  to  the  patient, 
and  its  time-saving  advantages  are  appealing  to  me  as  to  everyone,  and  I  employ 
it  wherever  it  shows  a  saving  of  time  compared  with  the  malleted  filling,  but  I  have 
been  forced  to  change  my  technique. 

Instead  of  carefully  trimming  down  all  overhanging  edges  I  leave  a  little  surplus 
over  all  margins  and  after  setting  and  allowing  the  cement  to  harden  fifteen  or 
thirty  minutes,  trim  down  the  edges  with  gold  finishing  burs  and  repeated  bur- 
nishings. 

In  doing  this  care  must  always  be  taken  that  the  tool  rotates  from  gold  to  margin. 
For  example,  if  I  finish  an  occlusal  filling  in  a  right  lower  molar  I  trim  the  labial 
margin  by  running  the  engine  the  regulation  way,  from  left  to  right,  but  reverse 
the  motion  when  working  on  the  lingual  margin  and  do  not  forget  to  lubricate  burs 
and  burnishers  with  vaseline. 

By  these  means  I  have  succeeded  in  closing  the  margins  perfectly  as  far  as  can 
be  determined  by  ocular  and  exploratory  inspection. 

This- sealing  of  margins  is  necessary  in  the  light  of  our  past  experience  with 
cements  of  the  consistency  used  in  setting  of  inlays,  which  is  the  same  as  has  been 
employed  for  a  few  decades  for  setting  crowns  and  bridge  work. 

I  have  removed  very  few  crowns,  etc.,  that  did  not  greet  me  with  that  foul  odor 
that  cement  stores  up  in  its  pores,  and  I  have  more  often  than  not  seen  decay  re- 
curring under  even  well-mixed  cement  fillings. 

The  thinner  the  cement  the  more  easily  is  it  washed  out  and  cracks  form  that 
invite    decay. 

In  cases  where  the  shrinkage  and  warping  of  the  filling  would  be  too  great 
to  overcome  by  burnishing,  I  employ  a  different  technique. 

The  gingival  margin  has  always  been  the  weakest  part  of  a  filling,  showing 
the  greatest  percentage  of  recurrence  of  decay,  and  it  is  also  the  vulnerable  point  of 
inlays.  As  it  is  in  most  cases  impossible  to  properly  burnish  gold  to  place  between 
the  teeth,  I  help  myself  by  beveling,  giving  the  edge  an  angle  of  about  12f)  degrees. 
The  corresponding  gingival  margin  of  the  inlay  will  show  a  V-shaped  form, 
the  outer  edge  of  which  I  burnish  inward  and  depend  on  the  malleting  to  open  it 
sufficienth'  to  make  it  fit  snugly.  If,  upon  examination,  I  find  any  opening,  I  repeat, 
and  only  after  being  certain  of  a  perfect  fit  will  I  cement  filling  into  place. — Items  of 
Interest. 

THE  CAST  CLASP 

By  W.   B.   Caldwell,   D.D.S.,   Hamilton,  Ohio. 

The  cast  clasp  is  the  most  accurate  clasp  that  can  be  made.  After  se- 
curing a  perfect  cast  from  a  plaster  impression,  proceed  to  burnish  No.  40  tin 
around  the  teeth  to  be  clasped,  which  will  keep  the  wax  from  adhering  to  plaster 
tooth,  then  take  inlay  wax  and  press  around  the  tooth,  carve  to  the  desired  shape, 
then  attach  a  small  piece  of  wax  for  a  lug,  remove,  place  on  sprue  wire,  and  inve.st; 
use  regular  clasp  metal  for  casting.  Cement  clasps  on  case  before  setting  up  the 
teeth,  to  hold  them  in  position. 

By  using  this  method  you  will  have  a  denture  that,  when  inserted,  will  give  a 
very  pleasing  result;  it  will  not  spring,  but  will  be  absolutely  firm. 


NUGGETS  OF  GOLD— INLAYS 

By  O.   E.   Lanphear,  D.D.S.,   Paw  Paw,   Mich. 

Our  profession  has  more  cause  for  thankfulness  than  any  other.  This  we  may 
say  reverently,  with  no  spirit  of  boastfulness  in  our  own  strength,  but  with  gratitude 
to  our  Creator,  who  has  blest  us  with  the  conditions  and  environments  which  have 
enabled  us  to  achieve  so  large  a  measure  of  well-being  and  happiness  for  our  fellows. 
To  the  members  of  our  profession  has  been  granted  the  inestimable  pleasure  of  strik- 
ing out  in  many  new  untried  lines  and  carrying  them  to  a  high  degree  of  excellence. 
We  are  the  heirs  of  the  ages.  We  have  had  to  pay  some  of  the  penalties  co-existent 
with  the  conditions  in  bygone  civilization,  and  in  the  face  of  these  difificulties,  which 
have  called  for  strenuous  vigor  and  effort,  success  has  attended  us  and  we  possess 
a  fixed  determination  to  wrest  from  the  future  the  measure  of  success  which  is  the 
reward  of  the  faithful. 

Success  in  the  dental  art  has  reached  a  great  altitude  through  the  special  effort 
expended  on  the  restoration  of  health  and  the  mitigation  of  pain.  These  have  been 
the  constant  themes  of  the  most  fertile  human  brains  of  their  time,  the  fruits  of  which 
their  possessors  have  laid  unsparingly  on  the  altar  of  human  progress.  Today  our 
fellow  men  pay  tribute  and  respect  to  the  profession  built  upon  the  results  of  our 
unceasing  labors.  Practical  and  experienced  clinicians  have  formulated  a  working 
hypothesis,  so  necessary  to  permanent  advancement  in  any  art,  and  we  point  with 
pride  to  the  acumen  displayed  by  our  profession  in  working  out  the  theories.  While 
much  is  accomplished  by  the  practical  clinician  it  is  becoming  more  and  more  a 
necessity  to  thoroughly  understand  the  theory  of  all  technical  procedure,  thus  placing 
the  art  as  far  as  may  be  in  the  domain  of  exact  science. 

Our  ranks  include  many  expert  manipulators  in  porcelain  and  gold,  each  having 
contributed  something  to  the  sum  of  professional  knowledge,  in  cavity  preparation, 
speed  or  permanency.  Some  few  furnish  records  of  systematic  investigations  with 
basic  data  to  aid  in  reducing  the  chances  of  failure  to  a  minimum.  Too  many  are 
content  to  understand  the  "how,"  with  no  knowledge  of  the  "?c'//v"  of  their  methods. 
This  accursed  professional  apathy  keeps  many  practitioners  from  attaining  the  front 
rank  and  leaves  them  narrow.  Let  us  be  broad  and  liberal,  discreet  and  discerning, 
willing  and  capable  in  the  service  rendered. 

For  the  past  decade  inlaid  fillings  have  occupied  a  prominent  place  in  our  work. 
Porcelain  and  gold  have  held  the  foremost  places  and  we  point  with  pride  to  our 
successful  operators  who  save  time  and  important  tissue  by  their  expert  knowledge 
and  scientific  technique.  While  we  pay  marked  deference  to  these  men,  many  of  us 
allow  our  energies  to  wane  and  our  ambitions  to  atrophy.  \\'c  should  be  able  to  use 
the  inlay  methods  where  discretion  demands,  for  the\-  ciiua! 

"Nature's  brag,  and  must  be  shown 
In  courts,  at  feasts,  and  high  solemnities, 
Where  most  may  wonder  at  the  workmanship." 

The  dental  art  requires  painstaking  study  and  careful  manipulation  to  obtain 
ideal  results  in  gold  inlays.  Trained  discretion  in  the  preservation  of  toolh  suii- 
stance  is  as  great  an  aid  to  iiermancncy  as  extension  for  prevention  or  retention. 


118  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

In  simple  cavities  the  seat  of  the  cavity  should  be  flat  and  parallel  to  the  plane 
of  the  defective  surface,  while  the  walls  should  be  nearly  at  right  angles  to  this  and 
slightly  divergent.  In  compound  cavities,  lateral  retention  is  secured  by  frictional 
planes,  dovetail  extension  or  pin  projection,  that  will  allow  the  model  to  be  removed 
without  distortion.  Any  deviation  from  the  desired  planes,  as  pits,  under  cuts  and 
spherical  depressions,  should  be  filled  to  within  one  millimeter  of  the  surface  with 
good  cement,  and  carefully  trimmed  to  allow  of  drawing.  When  this  has  set  the 
cavity  is  moistened  and  the  apex  of  a  warm  wax  cone  is  placed  against  the  deepest 
portion  of  the  cavity  and  the  remainder  is  pressed  to  place  with  the  fingers. 

In  compound  proximal  cavities,  a  strip  of  linen,  celluloid  or  dam  should  be  drawn 
tight  at  the  gingival  border,  for  it  greatly  facilitates  the  work,  especially'  in  cases 
extending  below  the  gingival  line.  It  forces  the  wax  tightly  against  the  cavity  walls 
and  gives  an  approximate  contour  to  a  border  which  demands  perfect  carving. 

The  wax  should  be  chilled  and  the  excess  removed  with  a  sharp  carver,  leaving 
the  occlusal  full;  now  heat  this  surface  a  little  and  ask  the  patient  to  bite.  He  is 
then  left  to  his  own  devices  for  a  moment  to  allow  him  to  give  it  a  natural  bite. 
When  the  wax  is  chilled  again  and  the  articulation  is  accentuated  by  carving,  the 
approximal  surface  is  given  a  full  contour  and  a  normal  contact.  Polish  the  surface 
of  the  wax  and  remove  cautiously  with  a  firm  point  and  a  steady  hand.  Give  the 
model  a  critical  examination  and  do  not  hesitate  to  return  it  to  the  cavity  if  there  is 
any  possibility  of  distortion.  If  assured  that  the  wax  is  a  perfect  prototype  of  the 
filling  insert  a  heated  sprue  pin  in  the  axial  plane  of  a  convex  surface.  This  will  aid 
the  gold  to  go  directly  to  its  destination  without  marring  the  investment  margins. 
See  that  no  pits  remain  at  the  union  of  the  pin  and  the  model.  Place  the  bare  end  of 
the  sprue  pin  in  the  crucible  former  in  a  position  that  will  bring  the  wax  near  the 
bottom  of  the  investment  ring.  Coat  the  wax  with  alcohol  and  immediately  pro- 
ceed to  apply  a  thin  mixture  of  the  investment  with  a  camel's  hair  brush,  forcing  the 
investment  along  under  the  film  of  alcohol,  thus  excluding  the  air.  Gradually  force 
this  layer  off  with  a  thick  mix  of  the  investment,  filling  the  ring  with  the  same  and 
bring  the  model  to  its  position  in  the  ring.  In  five  minutes,  when  the  investment  has 
set  enough  to  be  firm,  the  sprue  pin  can  be  heated  a  little  to  soften  the  wax,  and  re- 
moved with  the  crucible  former  on  it.  Now  invert  the  case  and  place  on  the  heater, 
where  it  is  slowly  brought  to  the  boiling  point  of  the  wax  (75  C),  when  the  wax 
comes  out.  From  this  point,  the  heat  may  be  carried  up  rapidly  and  some  of  the 
carbon  burned  out.  Do  not  carry  the  heat  higher  than  necessary,  as  it  has  a  tendency 
to  distort  the  space  left  by  the  vanished  prototype.  A  liberal  piece  of  gold  is  now 
placed  in  the  crucible  formed  in  the  investment,  heated  nearly  to  the  boiling  point; 
when  the  force  of  the  machine  is  applied  it  rushes  down  the  sprue  hole,  forcing  the 
air  through  the  thin  and  porous  investment,  filling  the  space  left  by  the  wax  and 
remaining  there  under  the  pressure  of  the  machine  until  congealed,  when  it  can  be 
cooled  rapidly  in  water.  The  inlay  may  be  pickled  to  remove  the  investment  mate- 
rial, the  excess  of  gold  cut  away  on  the  lathe  and  the  surface  given  the  desired  polish. 
Then  try  it  in  the  cavity.  Make  sure  of  the  borders  and  the  little  details  which 
insure  the  permanency  of  the  inlay.  When  satisfied  with  the  trial,  remove  the 
inlay  and  cement  to  place  with  a  rocking  hand  motion,  aided  by  the  mallet  in  most 
cases.  The  cavity  form  must  furnish  the  retention,  leaving  the  cement  to  hold 
the  inlay  in  position  and  give  thermal  immunity'.  The  margin  of  the  tooth  should 
be  cut  true  and  as  nearly  at  right  angles  to  the  surface  penetrated  as  the  structure 
of  the  tooth  and  the  cavity  outline  will  permit,  then  the  inlay  will  butt  the  cavity 


NUGGETS  OF  GOLD—INLA  YS  119 

margin,  forming  an  ideal  joint.  This  joint  siiould  be  absolutely  Bush  and  well 
burnished.  The  margins  of  inlays  should  be  accessible  for  convenience  in  working. 
Sharp  angles  at  the  cervico-buccal  and  lingual  aspects  of  the  approximo-occlusal 
fillings  should  be  avoided.  In  occlusal  cavities,  the  outline  of  the  cavity  should 
have  rounded  angles,  to  avoid  the  gold  wearing  away  the  corners  in  the  investment 
at  the  time  of  casting.  The  cavities  with  narrow  necks  are  apt  to  show  that  parts 
of  the  investment  have  been  worn  away  leaving  the  inlay  full  at  this  point.  It  will 
not  go  to  place  until  the  neck  is  narrowed  at  these  points. 

Let  us  bear  in  mind  that  while  we  have  mentioned  many  of  the  salient  points 
in  the  technology  of  the  cast  gold  inlay,  which  saves  frail  teeth  and  weak  enamel  walls, 
relieves  patients  of  many  of  the  nerve-racking  procedures  incident  to  the  placing 
of  the  rubber  dam,  the  condensation  of  foil  and  the  tedious  sitting,  it  alone  does  not 
constitute  professional  success.  The  profession  of  skill,  brilliancy,  honor,  social 
position  or  the  ability  to  get  the  nuggets  of  gold,  do  not  spell  success.  It  is  the 
frankness  of  expression,  largeness  of  heart,  flexibility  of  mind,  accurate  perception 
of  difficulties  and  true  discrimination,  that  makes  our  continued,  conscientious 
services  benefactions  of  the  race,  and  bring  to  us  the  appellation — Success. 

DISCUSSION 

Dr.  a.  C.  Runyan,  South  Haven,  Mich.:  I  am  not  an  expert  on  gold  inlays  but  I  believe  that 
they  have  their  special  place  in  dentistry. 

I  have  done  more  or  less  of  the  inlay  work  both  in  porcelain  and  in  gold.  I  find  that,  as  the  doctor 
says,  a  great  deal  of  the  success  depends  upon  technique,  and  the  more  that  we  take  pains  with  these 
little  details  the  more  successful  will  we  be  with  the  inlay  fillings. 

It  is  claimed  there  is  no  better  filling  than  a  cement  filling, provided  it  does  not  wash  or  deteriorate, 
or  become  eliminated  by  the  secretions  of  the  mouth.  Now  that  we  can  protect  them  with  gold  inlays, 
I  think  that  they  make  a  very  much  better  filling  than  any  other  filling  that  we  have,  except  the  esthetic 
clatm  of  inlay  porcelain.  Gold  inlays  are  better  than  poor  porcelain  inlays.  Porcelain  fillings 
have  a  great  many  faults.  We  cannot  use  them  at  times  where  we  can  use  gold,  because  of  their 
friability;  and  I  think  for  the  back  teeth  there  is  no  better  filling  than  the  gold  inlay,  properly  put  in. 

Dr.  Lani-heak:     I  wish  there  had  been  more  discussion  on  this  subject. 

There  were  several  important  points  that  I  wanted  to  see  brought  out  in  the  discussion.  I  have 
been  interested  in  the  work  Dr.  Price  has  been  doing  in  regard  to  the  shrinkage  of  the  mold,  and  as 
near  as  I  can  find  out  he  shows  a  shrinkage  of  about  15-1000  of  an  inch,  which  would  make  quite  a 
deficiency  in  a  filling.  If  we  can  get  an  investment  that  expands  the  space  at  the  moment  the  gold  is 
cast,  and  there  is  a  shrinkage  of  the  gold,  though  it  is  under  pressure,  perhaps  it  will  be  nearer  the  ideal 
filling.  A  good  many  operators  have  used  the  matrix  system  to  aid  in  overcoming  this  difficulty, 
and  they  cast  into  the  matrix,  which  becomes  part  of  the  inlay.  The  wax  is  built  to  perfect  contour 
and  the  casting  process  causes  a  very  slight  distortion.  With  this  method,  I  think,  there  is  nealry 
perfect  adaptation. 


120  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

LIMITATIONS  AND  USES  OF  THE  GOLD  INLAY 

By  H.  M.  Semans,  A.M.,  D.D.S.,  Columbus,  Ohio. 

We  have  passed  the  experimental  stage  so  far  as  the  uses  of  the  gold  inlay  are 
concerned,  and  its  limitations  are  controlled  only  by  any  other  time-proven  filling 
material  that  will  suit,  in  the  judgment  of  the  operator,  the  necessities  of  the  case. 

This  subject  does  not  exact  from  me  arguments  against  the  use  of  gold  inlays, 
rather  I  am  expected  to  observe  their  already  proven  use  while  I  try  to  show  why  and 
how  and  where  their  use  is  called  for  in  filling  tooth  cavities.  Please  keep  in  mind 
that  the  older  inlay,  porcelain,  at  the  hands  of  skillful  operators  has  established  itself 
not  only  as  our  ideal  esthetic  filling  material,  but  that  it  is  recognized  as  a  most  excel- 
lent permanent  stopper,  for  thousands  of  such  inlays  are  holding  forth  without  carious 
returns  about  their  environments.  Also  keep  in  mind  that  manj^  more  thousand 
gold  fillings  are  still  today  showing  to  us  that  they  are  capable  of  perfect  sealment  of 
the  cavities  they  occupy.  And  there  are  none  of  us  but  will  give  thanks  to  the 
persistent  efforts  of  those  few  enthusiasts  fifty  years  ago  who  by  such  efforts  gave  us 
amalgam,  up  to  the  present  time  our  greatest  posterior  tooth  preserver.  Only  a 
few  years  ago  we  had  no  other  thought  than  that  these  two,  gold  and  amalgam, 
placed  properly  against  tooth  w^alls,  were  par  excellent,  without  limitation  in  the 
proper  use  of  each  in  its  place;  in  fact,  nothing  else  was  used  except  gutta  percha  and 
cement.  But  hold!  like  the  crusaders  of  old  I  have  found  the  talisman,  cement 
oxyphosphate  of  zinc,  once  a  temporary  make-shift  for  frail  teeth,  cheap  fillings, 
nervous,  sickly  patients,  stopper  of  dressings,  scorned  by  all  as  a  permanent  filling 
material,  except  by  the  occasional  few  who  recognized  an  esthetic  worth  to  it, 
even  though  constantly  replaced. 

It  is  hard  to  tell  whether  it  was  the  solid  block  inlay  idea  of  itself,  or  else  some- 
thing to  help  cement  to  be  retained  in  a  cavity,  that  has  brought  about  inlaying  of 
cavities;  probably  the  groping  about  and  working  out  of  both  ideas.  However, 
today  we  accept  the  fact  that  inlays  without  oxyphosphate  of  zinc  are  as  impossible 
as  moon  beams  at  high  noon. 

First,  then,  where  are  gold  inlays  uncalled  for?  In  all  cavities  unlined  with 
oxyphosphate  of  zinc.  We  all  know  that,  only  let  us  always  keep  it  in  mind.  Next, 
in  all  the  six  anterior  teeth  which  will  warrant  porcelain  inlays,  chemical  porcelain 
cement,  and  gold  fillings.  We  are  now  occasionally  hearing  the  remark  that  porce- 
lain inlaying  has  had  its  day.  Yes,  some  kinds  of  porcelain  inlaying  has  had  its  day, 
and  most  of  us,  no  doubt,  have  helped  some  of  our  own  and  others'  porcelain  inlays 
to  have  their  day,  with  a  sigh  and  a-lack-a-day.  But  porcelain  inlaying  has  improved 
so  greatly,  and  bad  results  have  taught  us  so  thoroughly,  that  we  know  anterior 
tooth  cavities  which  allow  good  thick  edge  approach  of  the  inlay,  where  necessary, 
can  be,  and  are,  effectively  and  beautifully  filled  with  baked  porcelain.  Chemical 
porcelain  cements,  while  yet  in  an  experimental  stage,  are  showing,  under  wise  and 
careful  selection  of  the  place,  some  very  good  results.  All  small  cavities  in  anterior 
teeth  which  are  not  conspicuous  and  in  manj'  cases  large  proximal  cavities  which  are 
more  or  less  inconspicuous,  do  not  call  for  the  gold  inlay.  It  is  still  good  practice  to 
fill  such  cavities  with  gold  in  the  good  old-fashioned  way.  The  wide  wedging  and  broad 
cutting  away  of  tooth  structure  for  inlays  is  not  warranted.  It  would  seem,  then, 
that  I  have  very  nearly  eliminated  the  gold  inlay  for  the  six  anterior  teeth;  especially 
for  esthetic  reasons,  they  should  not  be  used,  if  possible  to  avoid  doing  so.  Yet 
under  certain  conditions  a  thin  frail  tooth,  not  having  a  great  amount  of  labial  sur- 


LIMITATIONS  AND   USES  OF  THE  GOLD  INLAY  121 

face  involved  might  wtxrrant  a  gold  inla\',  with  iridio-platinum  pin  and  [jrojier  lingual 
preparation  brace  against  stress  and  strain.  We  all  see  mouths  with  teeth  more  or 
less  shortened,  incisive  ends  badly  worn  down,  the  dentine  between  the  enamel 
layers  of  hard  to  soft  decay  always  connecting  up  with  proximal  cavities  or  leaking 
fillings;  gold  inlays  indicated  there?  Yes,  many  times.  Yet,  ideally,  what  about  the 
jacket  porcelain  crown? 

The  gold  inlay  with  porcelain,  baked  or  inlaid  into  it,  as  ad\-ocated  lately,  may 
work  out  to  be  a  most  excellent  combination  for  anterior  and  some  posterior  restora- 
tions; if  so,  then  to  that  extent  do  we  remove  a  limitation. 

Posteriorly,  gold  inlays  are  almost  unlimited.  The  cost  of  a  filling  of  course  is  a 
tremendous  factor  in  our  work,  so  I  must  immediately  qualify  that  statement. 
Amalgam  can  be  so  quickly  inlaid  in  almost  all  posterior  cavities,  and  made  very 
effective,  so  that  it  removes  the  necessity  of  gold  alone  as  a  posterior  inlay.  But  we 
must  remember  that  it  is  amalgam's  cheapness  over  gold  that  gives  it  its  great  ad- 
vantage. Laying  aside  wax  fillings  for  leisure  hour  casting,  or  laboratory  assistant 
casting,  and  the  use  of  impression  material  with  Price's  stone  cement  models  for 
subsequent  filling  and  casting  has  given  us  great  consei'vation  of  time.  The  ease  with 
which  amalgam  is  manipulated  as  against  the  labor  and  time  taken  to  mallet  in  a 
posterior  gold  filling  has  cost  almost  all  users  of  amalgam  enough  money  to  ha\'e 
bought  and  almost  maintained  that  coveted  automobile,  or  given  an  occasional  trip 
abroad.  In  the  minds  of  many  dentists,  gold  malleted  fillings  used  in  the  posterior 
teeth  have  become  ancient  history.  Yet  the  gold  filling  can  still  and  should  be  still 
used  in  most  of  the  pit  and  fissure  cavities.  On  the  other  hand,  we  can  average  up 
better  contour  and  contact  points  with  the  gold  inlay;  our  grooves,  cusps,  fossae  and 
ridges  can  be  perfect  reproductions;  the  restoration  of  all  frail  and  extensively 
decayed  teeth  is  now  almost  universal;  while  as  for  ease  and  comfort  to  both 
patient  and  operator,  there  is  no  comparison.  Gold  inlaying,  then,  in  posterior 
teeth,  has  wonderfully  enlarged  our  field  for  better  restoration. 

We  are  constantly  being  told  today  that  there  is  but  one  thing  that  stands  in  the 
way  of  inlays  as  our  ideal  fillings,  and  that  is  the  always  possible  dissolution  of  the 
cement.  This  objection  can  be  overcome  in  several  ways.  First,  prepare  the 
cavities  right  and  obtain  a  correct  inlay;  second,  set  the  inlay  as  Dr.  Taggart  tells  us, 
with  first  a  rocking  motion  so  as  to  flow  or  rock  out  all  the  cement  possible,  followed 
immediately  with  firm,  steady  pressure  for  twenty  or  more  minutes.  A  good  inlay 
in  a  properly  prepared  cavity  should  almost,  if  not  quite,  eliminate  the  edge  difficulty. 
But  if  it  does  not,  and  it  often  does  not,  then  finishing  bur  burnishers  will  spin  the 
gold  over  the  margins.  Lately  we  have  been  told  that  it  is  well  to  trumpet  or  be\-el 
out  more  than  we  used  to  do,  and  this  seems  to  be  good  advice.  Our  gold  will 
burnish  out  or  spin  out  under  the  dull  bladed  burs,  polishing  to  a  smooth  nicety  with 
disks  and  strips,  as  of  old.  xMso  we  have  lately  been  ad\ised  against  the  remo\-al  of 
quantities  of  our  gold,  both  to  economize  and  to  give  place  for  cement  to  get  into  to 
help  hold,  following  the  line  of  argument  that  the  closer  our  inlay  walls  approximate 
the  cavity  walls,  and  the  less  cement  we  retain,  the  greater  is  the  power  of  resistance; 
and  that  sounds  like  most  excellent  advice  and  a  scientific  truth,  for  small  and 
medium  sized  inlays  at  least. 

Pure  gold  seems  to  prove  itself  b^'  all  odds  our  best  material,  with  22k.  plate  a 
second  choice.  Pure  gold  has  proven  itself  to  be  so  much  stronger  and  better  able 
to  withstand  stress  and  strain  than  was  expected  of  it. 


122  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Dr.  Price's  use  of  stone  cement  models  to  cast  into  has  given  us  a  splendid  way 
to  obtain  perfect  proximo-cervical  enamel  edge  adaptations,  and  ver>'  much  of  the 
trimming  can  be  done  before  placing  in  the  tooth. 

We  are  all  quite  familiar  with  the  lamentations  from  some  dentists  over  the  fear 
that  operators  would  soon  lose  their  skill  and  cunning  because  of  the  fact  that  there 
will  be  much  abandonment  of  gold  fillings  in  favor  of  the  inlay.  Feared  as  much 
myself.  But  while  delving  lately  into  some  old  magazines,  I  was  very  much  enter- 
tained over  the  fears  of  the  old  regulars  that  the  new  fandangled  material,  cohesive 
gold  ("works  just  like  putty"),  as  against  the  continued  use  of  gold  foil  (non-cohesive) 
would  entirely  eliminate  skilfulness  and  manipulative  ability  from  the  dental  pro- 
fession. No,  indeed,  it  is  going  to  take  great  skill  and  manipulative  ability  to  place 
a  perfect  gold  inlay,  one  that  retains  its  seat  immovably  before  cementing,  except  in 
the  direction  of  its  desired  withdrawal,  one  that  closes  of  itself  the  margins,  one  that 
will  conserve  the  tooth  for  years,  one  that  will  restore  the  contact  point  so  splendidly 
that  there  will  be  no  "meat  spaces"  with  the  terrible  concurring  ailments  of  gum  and 
alveolar  tissue,  one  that  will  present  perfect  anatomical  restorations  of  all  its  surfaces, 
one  that  will  protect  enamel  walls  from  fracture,  in  fact,  one  that  will  do  that  which 
we  most  desire,  save  the  tooth  in  an  ideally  practical  manner. 


THE  GOLD  INLAY 

By  J.  V.  Conzett,  Dubuque,   Iowa. 


I  want  to  commend  the  use  of  the  gold  inlay  in  its  place,  but  it  should  be  used 
with  discretion,  and  to  be  successful  must  receive  the  same  careful  painstaking  at- 
tention that  is  given  to  the  gold  filling.  If  this  is  done  in  every  case,  if  the  operator 
strives  to  make  every  operation  better  than  the  last  one,  there  will  not  be  a  decline 
in  his  technical  ability  but  he  will  go  on  from  victory  to  victory,  for  "To  him  that 
overcometh  shall  be  given  the  crown  of  life."  I  can  not  close  without  urging  the 
profession,  and  particularly  the  younger  members  thereof,  not  to  abandon  the  use 
of  gold  foil  as  a  filling  material.  The  older  men  will  not.  They  know  the  value  of  it. 
But  aside  from  its  merits  as  a  filling  material,  I  know  of  nothing  that  will  so  perfect 
the  technical  ability  of  the  operative  dentist  than  will  the  mastery  of  gold  foil. 
The  man  that  can  make  a  good  gold  filling  has  acquired  a  technique  that  will  be  of 
the  greatest  assistance  to  him  in  the  mastery  of  any  other  material,  and  other  things 
being  equal,  the  man  that  has  gained  this  technique  will  make  a  better  operation 
with  any  other  material  than  one  that  has  not  acquired  it. — Dental  Review. 


CASTING  GOLD  ON  PORCELAIN 

By  E.  Cunningham,   Perry  Sound,  Can. 

At  last  I  have  been  successful  in  casting  againsc  porcelain  without  checking. 
I  use  a  flask,  the  dimensions  of  which  are  one  and  one-quarter  inches  in  diameter 
and  the  same  height.  After  coating  wax  with  silex  and  plaster,  I  fill  balance  of  flask 
with  Broph3''s  imperial  investment  compound  and  after  drying  I  place  in  a  coal  stove 
and  leave  till  it  is  all  red  hot.  Then  it  only  takes  a  few  minutes  to  melt  gold  and 
force  home,  and  as  there  is  quite  a  body  of  investment  around  the  tooth,  it  has  not 
time  to  cool  before  the  gold  comes  in  contact  with  it.  I  have  made  a  four-tooth  bridge 
by  this  method  and  all  facings  were  intact. — Dental  Review. 


CROWN  AND  BRIDGE  WORK 

By  J.  H.  Landry,  D.D.S.,  New  Orleans,  La. 

I  have  kept  in  touch  with  the  best  methods  of  crown  and  bridge  work  for  twenty 
years  and  can  enter  with  perfect  propriety  upon  a  discussion  of  the  exercise  of 
prudence  in  the  application  of  the  principles  of  crown  work  and  bridging  of  spaces. 

I  do  not  propose  to  criticise  or  pass  judgment  upon  methods  that  are  freely 
used  by  ethers. 

The  very  minutest  detail  of  mechanical  construction  will  not  be  given,  feeling 
such  to  be  unnecessary  and  I  will  deal  with  the  broad  underlying  principles  that 
govern  the  attachment  of  a  foreign  substance  to  a  root  in  the  mouth  as  a  substitute 
fo"  the  lost  crown,  and  the  attachment  of  one  tooth  to  another  to  support  substitutes 
for  the  missing  ones,  calling  upon  them  to  perform  duties  belonging  to  the  full  mem- 
brane. 

The  e.Kperience  and  success  of  so  many  years  has  given  this  class  of  work  the 
acknowledged  right  to  be  considered  among  the  most  useful  and  reputable  operations 
of  today;  but  the  question  arises,  what  has  been  the  effect  of  its  introduction  to  the 
dental  profession  for  good  or  evil?  Like  most  all  advanced  methods,  its  benefits  up 
to  the  present  time  have  been  in  restoring  and  preserving  roots  and  broken  down 
crowns  of  teeth  that  would  otherwise  have  been  lost,  thereby  improving  the  power 
of  mastication,  prolonging  life  and  health. 

How  many  times  has  there  been  a  loss  cf  good  roots  and  teeth  through  improper 
attachment  for  the  purpose  of  withstanding  a  strain  they  were  unable  to  bear,  by 
injudicious  fit — or  badly  fitting  bands,  causing  irritation  of  the  peridental  mem- 
brane? 

A  perfect  crown  must  provide: 

Firstly — A  natural  appearance  if  for  the  anterior  teeth. 

Secondly — A  Richmond  or  preferably  a  crescent  band  to  guard  against  splitting 
weak  roots. 

Thirdly — The  fit  should  be  perfect  so  there  can  be  no  dislodgment. 

Fourthly — To  preserve  the  interproximate  spaces  and  guard  against  all  irritation. 

Bridge  work  embodies  all  the  foregoing  dangers,  increased  proportionately  to 
the  greater  strain  it  is  called  upon  to  bear. 

The  collection  of  particles  of  food  or  other  decomposable  matter  between  the 
ridge  or  under  the  gum  may  be  avoided  by  making  the  surfaces  and  interspaces 
self-cleansing. 

The  Logan,  Bonwill,  Howe,  Davis,  White  and  all  other  porcelain  crowns  that 
are  used  have  certainly  the  advantage  of  a  more  natural  appearance  for  the  anterior 
teeth,  over  a  plate  tooth  backed  by  metal.  Of  the  ready-made  crown  I  consider  the 
Logan  less  desirable  owing  to  the  shape,  size  and  weakness  of  its  pin,  which  has  been 
the  cause  of  many  split  roots. 

Noting  the  value  placed  upon  a  band  for  the  security  of  the  crown  to  root  for 
so  many  years,  is  gradually  passing  to  a  crescent  or  no  band  at  all,  because  we  hear 
on  all  sides,  "keep  the  neck  of  the  teeth  free  from  deposit  of  calculus  or  anything 
that  might  irritate  the  gums,"  and  in  the  same  breath  we  are  told  to  "pass  the  bands 
up  well  under  the  free  margin  of  the  gum,  regardless  of  such  irritation." 


124  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Dr.  E.  Palmly  Brown  was  the  one  who  brought  before  the  profession  the  system 
of  porcelain  bridges,  anchored  with  gold  fillings,  malleted  about  a  bar  extending  into 
the  tooth. 

Now  the  dental  profession  is  greatly  indebted  to  Dr.  Taggart  for  his  methods  of 
casting  gold  inlays  and  for  the  attachment  of  crowns  and  bridges  that  will  save  the 
necessity  of  sacrificing  the  whole  structure  of  many  good  teeth  for  bridging. 

I  very  seldom  use  a  band  any  more;  it  is  unsightly,  unnecessary,  and  with  a 
good  pin  you  will  get  all  the  strength  wanted,  as  all  the  force  is  outward.  Sometimes 
a  band  is  necessary  in  a  lower  tooth  where  recession  of  the  gums  has  left  space  for  a 
very  short  pin  to  be  used  and  a  good  sized  band  can  be  used  and  not  be  seen. 

In  preparing  roots  for  crowns  I  always  seal  the  apex  before  reaming  canal  for 
the  reception  of  a  pin  and  much  future  trouble  will  be  avoided. 

The  dowel  should  be  made  of  platinum  and  iridium  wire  only,  all  other  kinds 
are  not  safe  if  subjected  to  much  heat. 

Before  crowning  a  tooth  always  devitalize.  Should  pyorrhea  alveolaris  develop 
after  a  few  fears  in  that  mouth,  those  teeth  will  be  free  from  the  disease  while  one 
sound  one  after  another  will  be  lost  unless  they  are  carefully  treated. 

I  never  take  an  impression  for  crowning  of  the  anterior  teeth;  my  patients' 
mouths  are  my  true  models,  and  besides  saves  lots  of  time.  Get  size  and  shade  of 
facing  ready  before  the  appointed  time  of  patient. 

After  reducing  the  root  to  the  desired  shape,  take  No.  33  gauge  pure  gold  and 
burnish  to  the  root,  leaving  it  a  little  overlapping  in  lingual  portion  to  burnish  over 
root  that  will  take  the  shape  of  a  crescent  band.  Should  you  desire  a  large  crescent 
band,  fit  one  and  solder  to  pure  gold  before  burnishing  same  over  root,  then  punch 
hole  through  plate  and  push  pin  to  place,  remove  and  solder  (the  pin  having  been 
previously  closely  fitted  to  the  canal),  replace  same  on  root,  reburnish  to  water  tight 
joint  and  then  trim  to  fit  periphery  of  root.  Grind  facing  to  fit,  back  it  up  with  No. 
33  gauge  gold,  wax  and  attach  the  cap  in  mouth,  remove  crown,  finish  waxing  as  you 
want  it,  box  cutting  edge  and  sides,  invest  and  solder.  When  polished  you  have  a 
crown  which  fits  perfectly  over  entire  root  and  in  cementing  to  place  a  thin  film  of 
cement  will  be  caught  between  the  attachment  but  not  enough  to  weaken  the  strength 
of  your  crown.  An  open-faced  crown  is  not  a  good  anchorage  for  a  bridge,  for  the 
attachment  to  be  any  way  weak  will  cause  a  failure. 

It  is  almost  impossible  to  lay  down  any  set  rules  to  follow,  but  I  will  mention  a 
few  cases  where  a  bridge  will  do  good  service.  In  making  a  bridge  of  twelve  or 
fourteen  teeth  it  is  necessary  to  have  not  less  than  four  good  teeth  or  roots,  including 
the  two  cuspids  and  two  solidly  set  molars,  that  will  carry  a  bridge  for  good  service. 
In  this  case  the  cuspids  should  be  cut  off  and  crescent  crowns  used,  the  molars  should 
be  devitalized  and  two  gold  caps  made  for  the  abutment. 

In  case  where  right  central  and  lateral  are  missing,  left  lateral  and  first  and  second 
bicuspid  out,  I  would  make  that  bridge  in  two  pieces  by  using  right  cuspid  and  left 
central  to  carry  right  central  and  lateral,  left  cuspid  and  first  molar  to  carry  two  left 
bicuspids  and  lateral.  In  all  cases  a  good  bridge  can  be  made  from  a  cuspid  to  a 
third  molar.  The  two  centrals  will  carry  the  two  laterals  and  the  laterals  the  two 
centrals,  and  so  on.  A  loose  root,  if  properly  treated,  will  get  firm  and  strong  again. 
I  will  now  touch  lightly  upon  an  important  part  to  consider.  In  trimming  molar 
teeth  you  should  always  have  in  mind  what  the  shape  of  the  tooth  would  be  if  cut 
across  below  the  margin  of  the  gum.  The  barrel  shape  entirely  taken  off  to  nearly 
one-sixteenth  of  an  inch  below  the  gum  line  leaving  the  sides  of  the  tooth  parallel 


CROWN  AND  BRIDGE   WORK  125 

so  that  the  band  will  hug  the  tooth  tightly.  Take  a  lower  first  molar.  The  buccal 
side  swells  out  very  great,  but  the  anterior  surface  not  so  much.  After  this  tooth  has 
been  properly  shaped  it  will  be  nearly  square  with  the  corners  rounded. 

In  many  cases  after  trimming  the  mesial  and  distal  surfaces  it  will  be  necessary 
to  trim  only  the  lingual  side,  as  the  tooth  often  leans  over  towards  the  tongue,  the 
band  will  pass  over  the  enamel  on  buccal  side  and  touch  the  tooth  below  gum  margin. 

The  most  difficult  part  to  reach  in  trimming  is  the  anterior  surface  of  the  lower 
molar.  If  you  will  take  notice,  an  upper  molar,  when  prepared,  is  found  to  be 
altogether  different  from  the  lower,  being  triangular  in  shape.  This  will  sometimes 
vary,  the  palatal  root  being  as  broad  as  the  two  buccal  roots,  but  not  very  often. 
A  great  deal  must  be  cut  from  the  mesial  and  distal  surfaces  of  the  posterior 
teeth  and  very  little  from  the  buccal  and  palatal  or  lingual  sides.  The  cusps 
should  be  ground  away,  so  a  thick  metal  cusp  can  be  placed  on  the  band  to  insure  a 
strong  bridge. 


HOLLOW  CAST  INLAYS 

By  W.  S.   Payson,   Castine,   Me. 


In  making  a  hollow  cast  inlay  after  the  wax  model  is  on  the  sprue,  build  up  the 
investment  on  the  sprue  side  and  let  it  harden;  then,  with  a  small  drill  in  the  engine, 
drill  out  the  back  of  the  wax  to  the  extent  of  the  cavity  wanted  in  the  back  of  the 
inlay,  and  finish  the  investment. 

The  first  investment  holds  the  wax  firmly.  The  drill  is  better  than  a  lancet  for 
cutting  the  wax.     Particles  of  wax  can  be  brushed  away  with  a  very  fine  brush. 

A  hollow  inlay  is  more  firmly  held  by  the  cement,  and  less  gold  is  used. — Dental 
Cosmos. 


AN  ANTERIOR  CAST  BRIDGE 

By  E.  Cunningham,   Perry  Sound,  Can. 

Prepare  roots  for  abutments  and  adjust  platinum  caps.  Pass  pins  through  the 
caps  and  attach  with  solder.  Take  bite  and  impression;  make  model  and  grind 
facings.  Remove  pins  and  caps  from  the  model  and  enlarge  pin  holes  so  the  case 
will  draw  easily.  Replace  abutments  on  model  and  wax  all  facings  in  position, 
attaching  sprue  so  that  gold  will  not  flow  direct  against  the  porcelain.  The  case 
is  now  rcad>-  to  be  invested  and  cast. — Dental  Review. 


TO  HOLLOW  OUT  WAX  MODEL  FOR  GOLD  INLAY 

By  S.  T.   Neill,  Clinton,   Mo. 

An  appliance  costing  a  trifle  can  be  made  in  a  minute  or  two.  Renioxe  the 
middle  point  from  a  hypodermic  needle,  hold  it  in  Bunsen  burner,  and  pull  it  out 
with  pliers;  slip  a  foot  of  rubber  tubing  en  er  the  large  end  of  the  needk',  warm  it  in 
the  flame;  suck  gently  with  the  lips  on  the  tubing,  while  holding  the  warm  point 
against  the  excess  wax  of  the  model.  Burn  out  wax  in  the  needle  point  by  holding 
in  the  flame,  and  blowing  through  it. — Western  Dental  Journal. 


CASTING  OF  LARGE  BRIDGES 

By  W.  H.  Hayden,  D.D.S.,  Youngstown,  Ohio 

Editor  The  Dental  Summary: 

Dear  Doctor: — I  have  read  with  much  interest  all  that  I  have  seen  in  any  of  the 
magazines  with  regard  to  casting,  especially  bridge  casting  and  other  large  cases. 
In  the  February  Summary  I  noticed  a  little  item  by  Dr.  J.  G.  Lane,  of  Philadelphia, 
saying  that  large  pieces  should  not  be  attempted  because  of  shrinkage  and  consequent 
misfit. 

I  have  cast  at  least  twenty  bridges,  of  three  to  six  teeth  each,  on  two  and  three 
abutments,  and  two  eight-tooth  pieces  on  four  abutments,  one  having  eight  facings, 
molding  these  in  the  mouth  without  impression  or  model,  and  I  must  say  I  never 
inserted  as  fine-fitting  bridges  by  any  other  method. 

Here  is  an  illustration  that  may  help  readers  to  understand: 


Description: — Two  dummies,  porcelain  faced,  anchored  by  an  inlay  in  occlusal  approximal  sur- 
faces of  second  bicuspid,  with  post  in  root  canal,  and  distally  by  an  inlay  in  a  compound  mesial  and 
occlusal  cavity  in  third  molar. 

Description: — Two  dummies,  porcelain  faced,  anchored  by  an  inlay  in  occlusal 
approximal  surfaces  of  second  bicuspid,  with  post  in  root  canal,  and  distally  by  an 
inlay  in  a  compound  mesial  and  occlusal  cavity  in  third  molar. 

I  would  advise  placing  an  iridio-platinum  wire  of  generous  size  throughout  such 
pieces,  and  a  very  convenient  method  of  doing  that,  in  such  cases  as  that  shown,  is 
to  bend  the  wire  that  forms  the  post  in  the  bicuspid  at  right  angles,  and  letting  it 
extend  into  the  cavity  in  the  molar,  thereby  greatly  facilitating  waxing-up  and  carv- 
ing.    It,  of  course,  adds  great  strength  to  the  finished  piece. 

It  is  needless  to  say  that  I  use  the  Elgin  casting  appliance,  and  cast  directly 
onto  the  facings,  the  checking  of  a  facing  occurring  so  seldom  as  not  to  be  taken  into 
consideration. 


MAKING  A  RICHMOND  CROWN  WITHOUT   THE   USE  OF  SOLDER— A 
DETACHABLE  PIN  FACING 

By  T.  C.  Hutchinson,  D.D.S.,  Decorah,  Iowa 

My  principal  reason  for  recommending  this  method  of  making  a  Richmond 
crown  to  the  profession  is  the  simplicity  of  technic  used. 

A  crown  is  a  failure  when  it  dees  not  protect  the  root  to  which  it  is  fastened 
against  decay  and  breakage,  when  it  is  out  of  alignment,  and  when  it  is  off  color. 

As  is  often  the  case,  the  dentist  has  not  the  shade  required  or  the  size  needed  in 
an  all-porcelain  crown,  so  he  uses  the  nearest  one  to  it  and  cements  it  to  place;  so  I 
will  endeavor  to  show  that  any  porcelain  facing  or  tooth  can  be  used  in  the  making 
of  this  crown.  I  will,  however,  describe  the  use  of  a  pin  facing  and  its  detachable 
features.  Other  facings  on  the.  market  can  be  used,  following  the  same  method, 
but  in  case  of  a  Steele  or  Evslin,  the  facing  is  slipped  off  and  the  pin  or  the  made-to- 
order  facing  is  lifted  out  from  its  wax  seat. 


Fig.  1. — Root  trimmed  and  post  in  position, 
ready  for  wax  crown 

Root  Prepar.\tion — A  banded  root,  when  properly  prepared  is  the  surest  and 
safest  method  of  saving  a  root  from  decay  or  breakage,  and  should  be  used  in  all 
cases  where  the  crown  is  to  act  as  an  abutment  for  a  bridge,  especially  on  single- 
rooted  teeth. 

Great  care  should  be  used  in  making  the  band  snug  fitting  and  without  irritation 
to  the  soft  tissues.  A  crown  with  coping  of  gold  is  much  better  than  a  poorly 
fitted  band. 

The  root  should  be  trimmed  below  the  gum  line  on  labial  and  palatal  surfaces 
and  left  high  in  center;  this  prevents  any  backward  or  forward  movement. 


128  PILA.CTICAL   MANUAL   OF    DENTAL    CASTING 


Fig.  2 


Fig.  3 


MAKING  A  RICHMOND  CROWN  WITHOUT  THE  USE  OF  SOLDER     129 

Post — In  reaming  the  canal  out  for  the  i)ost,  make  it  just  large  enough  so  that 
the  post  will  fit  in  snugly.  Use  Irridio-platinum;  let  it  extend  out  of  root  about 
1-16  inch,  bend  the  part  that  protrudes  palatally;  then  remove  and  melt  a  little 
solder  to  this  point.  The  object  of  this  is  to  insure  a  union  of  post  to  the  cast  gold. 
Use  16k  solder,  as  this  is  a  low  fusing  solder  and  the  cast  gold  striking  it  will  cause  it 
to  melt  and  thereby  fuse  with  rest  of  crown.     Note  Fig.  1. 

Facing — Select  facing  so  as  to  match  in  color  and  size,  and  grind  the  cutting 
edge,  so  as  to  have  the  wax  and  finally  the  gold  protect  it.  Fit  the  gum  edge  ap- 
proximally,  just  so  it  extends  to  the  gum  line;  then  oil  the  facing  on  all  sides,  the 
pins  especially,  and  select  a  mold  on  the  Anterior  Hutchinson  Wax  molding  plate 
and  place  facing  in  labial  or  buccal  side  of  same;  then  pour  the  wax  in  hot,  but  not 
too  hot  (wax  which  is  too  hot  will  absorb  the  oil  which  is  to  act  as  a  lubricant  and  you 
will  have  a  time  removing  facing).  Another  method  is  to  soften  the  wax  over  a 
flame  and  press  to  fill  mold  with  the  end  of  a  match  or  some  other  soft  wood.  After 
this  take  a  hot  spatula  and  trim  ofif  the  surplus  wax;  then  remove.     See  Fig.  2. 


Fig.  4 

Cool  the  wax  and  then  hold  between  finger  and  thumb  (Fig.  3)  and  heat  that 
surface  which  is  to  be  forced  against  the  root  and  post.  Be  sure  that  the  alignment  is 
right,  then  cool  and  remove.  Take  an  old  broach  (smooth),  (Fig.  4)  heat  it  and  run  it 
around  the  post  to  make  it  firm,  and  with  a  wax  knife  trim  off  the  surplus  wax  around 
root  impression,  also  around  the  facing;  then  put  in  place  in  mouth  to  see  that  no  dis- 
tortion has  taken  place  (Fig.  5).  Then  remove  and  take  a  piece  of  sticky  wax, 
soften  and  place  against  facing,  removing  it  from  its  wax  seat,  and  in  the  pin  holes 
place  the  carbon  points,  which  being  the  same  size  as  the  pins  will  go  to  place  without 
any  unnecessary  forcing.  Place  the  sprue  at  the  thickest  part  of  wax,  invest  and 
cast;  after  this  is  done  clean  and  burn  out  carbon,  and  cement  to  place.  The  carbon 
points  can  be  had  from  your  dealers. 

Very  often  we  meet  with  cases  where  the  bite  is  close  and  an  ordinary  facing  is 
too  thick,  or  we  may  have  a  case  of  an  extremely  small  tooth  to  crown.     I  take  any 


130  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

vulcanite  tooth,  grind  it  down  to  fit  so  tiiat  you  do  not  depend  upon  pins  for  re- 
tention, but  make  it  just  as  you  would  an  inlay  for  any  single  surface  of  a  natural 
tooth.  Oil  it  as  above;  in  fact,  go  through  the  same  procedure  as  described  for  the 
other  facings. 

DIRECTIONS  FOR  USING  HUTCHINSON  WAX  MOLDING  PLATES 

Of  all  classes  of  work  done  bj'  the  dentist,  there  is  none  that  gives  so  much  com- 
fort to  the  patient,  and  places  the  mouth  in  its  most  natural  condition,  as  good  fitting 
crown  or  bridge  work.  There  is  no  line  of  work  that  advertises  ethically,  or  brings 
the  dentist  in  more  cash  than  crown  and  bridge  work.  It  has  been  the  object  of  Dr. 
Hutchinson,  in  devising  the  Hutchinson  wax  molding  plates,  to  give  the  dentist  an 
easy  means  of  accomplishing  the  best  of  results  with  the  least  amount  of  trouble. 
The  making  of  crowns  and  bridges  with  the  Hutchinson  system  has  made  it  possible 


Fit;.   :> 

for  the  novice  to  do  as  good  work  as  the  most  expert.  In  fact,  it  is  a  pleasure  to  do 
this  class  of  work.  It  not  only  does  fast  work,  but  it  enables  you  to  do  artistic, 
perfect-fitting  dummy  work.  We  also  show  you  how  to  save  gold;  make  lighter 
bridge  work,  yet  stronger  than  by  the  old  method  of  soldering.  Many  mouths  have 
been  ruined  by  having  too  heavy  a  bridge,  which  weighed  down  the  abutting  teeth, 
causing  them  to  elongate  and  loosen,  and  finally  come  out.  By  the  aid  of  the  plates, 
you  will  find  an  incentive  to  talk  crown  and  bridge  work;  you  will  do  more  of  it, 
and  the  price  of  the  plates,  you  have  made  over  and  over  again  by  having  had  them. 
The  dentist  who  is  making  the  money  today  is  he  who  has  aiound  him,  in  his  office 
equipment,  instruments  which  will  aid  him  to  do  work  faster,  better,  and  with  less 
worry  to  himself  and  patient. 

The  large  plate  contains  one  hundred  and  fifty-eight  molds  of  the  buccal  and 
occlusal  surfaces  of  the  bicuspids  and  molar  teeth. 

There  are  molds  of  bicuspids  and  molars  singly,  and  in  pairs,  and  also  molds  of 
the  bicuspids  and  molars  united,  so  that  you  can  get  any  desirable  combination  of 
the  posterior  teeth  that  may  be  required  for  any  case. 

The  molds  are  perfectly  smooth,  and  the  arrangement  is  so  perfect  that  you  have 
an  alignment  of  teeth  which  defy  the  most  skilled  carver. 

We  have  carefully  selected  and  arranged  a  large  variety  of  sizes,  both  in  length 
of  mold  and  also  the  width. 


MAKING  A  RICHMOND  CROWN  WITHOUT  THE  USE  OF  SOLDER     131 

To  reproduce  a  mold,  be  sure  to  oil  the  mold  with  a  thin  coat  of  3-in-l  oil;  then 
take  a  spoon  and  melt  base  plate  wax  and  pour  into  mold;  let  it  cool,  then  with 
a  hot  spatula  trim  off  the  surplus  wax,  and  remove  from  mold. 

Now,  having  your  wax  teeth  and  your  plaster  model  ready,  you  can  bend  this 
wax  dummy  any  way,  and  yet  keep  the  forms,  as  made  by  the  plate,  perfect;  you 
then  adapt  it  to  the  model,  getting  the  contour,  holding  the  articulator  closed,  press 
the  occlusion.  You  now  trim  off  wax  where  needed,  and  take  a  minute  amount  of 
oil  of  cajeput,  soft  gauze  or  the  like,  and  smooth  all  surfaces,  and  then  your  dummy 
is  ready  for  the  investment. 

Be  sure  to  use  Hutchinson's  wax  or  common  base  plate  wax  in  conjunction  with 
the  plate.    It  is  necessary  to  have  a  pliable  wax.    It  burns  out  as  well  as  any  inlay  wax. 

To  make  a  hollow  dummy,  oil  the  mold  to  be  used,  then  pour  the  wax  in  hot,  and 
while  the  wax  is  still  in  this  heated  liquid  form,  take  a  roll  of  absorbent  cotton  and 
immergc  into  said  mold.  The  hotter  the  wax,  the  quicker  the  cotton  absorbs,  and 
the  thinner  will  be  the  dummy.  This  will  leave  a  uniform  thickness  of  wax  deposited 
in  the  mold.  You  can  add  more  wax  on  the  occlusal  surface,  where  thickness  is  re- 
quired. Then  remove  from  the  mold  and  adapt  to  your  model  and  obtain  occlusion 
as  in  solid  dummies,  then  cast  and  solder  a  backing,  or,  if  you  don't  want  this  hollow 
dumm\-,  but  wish  it  solid,  vet  you  don't  want  the  weight  that  an  all-solid  dummv 


will  make,  nor  do  you  want  the  gold  expense  that  this  large  dummy  would  necessitate. 
Listen!  I  will  shotv  hoiv  to  get  away  from  both  of  these  objections  and  yet  have  a  better 
dummy  and  a  stronger  one  than  though  it  were  solid,  and  still  have  an  all-gold  appear- 
ing dummy. 

First,  select  a  mold  that  suits  \'our  case,  then  oil  it  and  pour  it  full  of  hot  wax 
let  cool  and  trim  off  the  surplus,  and  then  fit  it  to  your  model,  trimming  where 
needed.  You  now  have  the  size  and  form  of  the  dummy,  which  is  to  be  used  for 
your  case.  Second,  oil  the  same  mold  again  and  pour  the  wax  in  hot,  and  with 
absorbent  cotton  suck  out  most  of  the  liquid  wax.  Third,  take  an  old  vulcanite 
tooth  having  platinum  pins  (Fig.  No.  1).  Grind  the  surface  off  and  bend  the  pins 
back  as  in  Fig.  2.  Now  set  in  the  mold,  which  has  the  thin  film  of  wax,  and  press 
against  the  buccal  surface,  allowing  for  sufficient  space  approximately  and  occlusally; 
you  then  melt  wax  hot  and  pour  into  mold,  covering  completely  the  porcelain, 
leaving  the  pins  exposed  (Fig.  3).  The  object  of  having  the  pins  exposed  is  to  catch 
in  the  investment  material  and  hold  the  porcelain  in  position,  while  in  the  act  of 
burning  out  the  wax  and  casting  metal  around  it.  If  you  were  to  cut  this  dummy 
after  casting,  you  would  find  a  box  effect,  which  has  proven  to  be  as  strong  as  though 
it  were  all  solid  metal.  By  using  this  method  you  are  not  only  saving  from  one- 
half  to  two-thirds  the  gold  which  a  solid  dummy  would  take,  but  you  are  making  a 
better  dummy.  One  that  is  not  over- weighted,  not  so  ruinous  to  the  teeth  they  are 
fastened  to,  and  consequently  one  which  will  have  more  lasting  qualities. 


132  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

In  a  short  time  we  will  have  for  the  market,  porcelain  cores  with  gold  pins,  so 
that  after  casting  there  will  be  no  perceptible  means  of  knowing  where  the  pins 
protrude;  until  then  you  are  at  liberty  to  use  the  above  means. 

To  make  the  backing  for  Steele  facings,  Evslin,  or  any  detachable  facing: 

Place  facing,  after  having  ground  to  fit  your  case,  and,  having  trimmed  the  cut- 
ting edge,  place  in  a  mold  which  holds  it  approximately,  and  oil  both  the  facing  and 
the  mold,  and  pour  the  wax  in  quite  hot  and  let  it  cool,  and  then  trim  wax  off.  You 
then  adapt  it  to  your  model  and  obtain  occlusion  and  trim  off  the  overlapping  wax, 
and  leave  enough  wax  for  protection  to  the  facing  at  the  cutting  edge;  then  with  a 
piece  of  sticky  wax  heat  and  place  against  facing,  letting  cool  a  second,  and  then, 
in  the  case  of  a  Steele  or  Evslin  facing,  slide  off  from  wax.  Place  the  sprue  wire 
on  the  palatal  surface  of  wax  and  invest  and  cast. 

When  using  the  pin  facing,  fit  the  facing  and  bevel  the  cutting  edge  towards  the 
buccal  surface,  have  the  pins  parallel,  oil  with  3-in-l  oil,  and  place  in  mold,  and  pour 
hot  wax  as  above;  let  cool,  trim  off  the  surplus  wax,  adapt  to  model.  You  will  note 
how  much  easier  it  is  to  obtain  protection  for  your  facing  with  wax  than  it  would  be 
with  plate  gold  and  solder.  When  you  have  perfected  the  fit  to  the  model,  trim  off 
overlapping  wax  as  above,  and  use  sticky  wax  to  remove  facing;  then  in  the  pin 
holes  place  a  piece  of  carbon  point  which  is  the  exact  size  of  the  pins;  invest  and  cast, 
and  after  casting,  burn  out  the  carbon  and  then  cement  to  place. 

THE   ANTERIOR   PLATE   AND   ITS    USE 

This  plate  contains  mostly  molds  of  the  anterior  teeth  of  various  sizes  and  shapes, 
also  molds  of  the  full  crown  surface  of  bicuspid  and  molar  teeth,  and  some  extremely 
large  molds  of  the  bicuspid  and  molar  teeth  for  dummy  purposes.  It  is  especially 
adapted  where  facings  are  to  be  used  for  crown  work.  There  are  so  many  features 
about  this  plate  in  the  making  of  crowns  and  dummies,  that  it  will  be  used  often 
and  become  indispensable  to  the  busy  dentist. 


THE  CAST  CLASP 

W.  B.  Caldwell,  D.  D.  S. 


The  cast  clasp  or  band,  used  in  retaining  partial  dentures,  is  found  to  be  quite 
satisfactory,  made  after  the  following  method:  First,  moisten  plaster  tooth  to 
prevent  wax  from  adhering,  soften  inlay  wax  and  shape  to  desired  thickness  and 
width;  press  around  plaster  tooth  as  far  as  clasp  should  extend;  (also,  in  cases  where 
molars  or  bicuspids  are  to  be  clasped,  and  the  articulation  will  permit,  allow  a  spur 
of  wax  to  extend  over  into  the  sulcus)  by  so  doing  the  clasp  will  not  allow  the  plate 
to  settle,  remove  the  wax  after  having  shaped  to  suit  the  case,  and  invest  as  usual. 
If  a  lug  is  desired,  shape  and  unite  with  wax  clasp,  cast  in  one  piece. 

Another  Method — Take  a  separate  impression  of  tooth  to  be  clasped,  pour 
a  cast  of  plaster  and  XXX  silex,  equal  parts,  having  cast  prepared,  melt  inlay  wax 
and  paint  it  on  tooth  over  area  to  be  covered  by  clasp,  then  invest  without  removing 
wax  from  tooth.  Care  should  be  taken  not  to  have  clasp  too  thin  as  the  cast  metal 
is  more  liable  to  break  than  clasp  plate.  A  partial  denture  constructed  with  cast 
clasps  is  very  pleasing  when  inserted  and  quite  practical,  as  there  is  no  spring  or 
rocking   to   the   denture. 


THE  CAST  ALUMINUM  PLATE 
By  Robert  Seymour,  D.D.S.,  Philadelphia,  Pa. 

A  plaster  impression  is  taken  of  the  case  in  the  usual  manner,  and  if  a  vacuum 
chamber  or  relief  is  needed  it  is  cut  in  the  impression.  This  is  then  given  a  thin  coat 
of  equal  parts  shellac  and  sandarac.  When  thoroughly  dry  an  additional  coat  of 
sandarac  varnish,  when  quite  dry  a  model  of  silex  and  plaster  in  the  proportion  of 


No.  1 

three  of  the  former  and  one  of  the  latter  is  made,  always  taking  the  precaution  to 

thoroughly  soak  the  impression  in  water  before  running  the  model.     (See  cut  No.  1.) 

The  silex  I  use  for  this  purpose  is  a  slightly  coarser  grade  than  that  used  for 

inlay  investment.     This  will  give  a  harder  model  and  still  produce  a  smooth  surface 


No.  2 


134 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


on  the  casting.  The  plate  is  now  waxed  in  the  usual  way,  using  tennax  wax,  as  it  is 
thinner  than  the  ordinary  base  plate. 

The  following  additions  will  be  noted  in  cut  No.  2: 

(a) — Plate  spurred  or  scored. 

(b) — Wax  rim  inside  and  out. 

(c) — Gateways. 

(d) — Sprue. 

The  sprue  may  be  a  No.  10  wire  as  shown  in  No.  2,  but  we  prefer  a  short  wax 
sprue  as  shown  in  No.  3. 

The  plate  being  ready  to  invest,  it  is  wise  to  place  it  in  water  and  allow  it  to 
absorb  all  it  will  take  up.  The  case  is  now  invested  in  the  lower  half  the  same  as  an 
ordinary  rubber  case,  bringing  the  investment  to  the  edge  of  the  wax.  When  this 
is  properly  trimmed  place  a  V-shaped  groove  encircling  the  model  a  short  distance 


ijimiiniuiiiii 


No.  3 


from  the  wax.  This  surface  is  now  given  a  slight  coat  with  oil  and  afterwards  brush 
lightly  over  with  powdered  soapstone;  where  the  rugae  surface  has  been  transferred 
by  means  of  tin  foil,  as  in  the  case  shown,  this  tin  should  also  be  slightly  oiled. 

The  second  half  of  the  flask  is  now  placed  in  position  filled  with  investment, 
taking  the  precaution  to  shake  it  well  to  place;  while  this  is  still  soft,  a  recess  is  cut 
away  in  the  central  opening  of  the  flask,  until  the  short  wax  sprue  is  exposed;  this 
forms  a  crucible,  for  the  subsequent  melting  of  the  metal.  After  the  investment  has 
become  hard  the  flask  is  subjected  to  dry  heat  for  a  few  moments  and  separated;  the 


THE  CAST  ALUMINUM  PLATE 


135 


entire  base  plate  of  wax  is  readily  removed  and  the  only  portion  of  wax  left  to  be 
burned  out  is  that  contained  in  the  gateways  and  sprue.  The  case  is  now  heated 
on  the  furnace,  and  if  any  carbon  is  left  on  the  surface  of  the  model  it  can  be  readily 
removed  with  the  blow-pipe,  as  the  entire  surface  is  exposed  and  has  a  great  advan- 
tage over  the  closed  flask  method,  as  it  is  difficult  to  burn  out  such  a  large  quantity 


No.  4 

of  wax,  and  if  this  is  not  done  the  resulting  cast  is  a  failure.  This  is  true  in  both 
systems  of  casting  where  pressure  is  placed  directly  against  the  molten  metal,  or  the 
method  of  creating  a  vacuum. 

When  the  case  is  hot,  the  upper  part  of  the  flask  is  again  placed  in  position  and 
it  will  locate  itself  by  means  of  the  V-shaped  depression,  which  was  cut  in  the  first 
half,  as  the  second  half  of  the  flask  will  have  its  counterpart.  It  also  forms  a  guard 
to  prevent  escape  of  the  metal  from  the  flask. 


No. 


No.  4  shows  a  crossed  section  of  case  at  this  stage.  Tlic  cup  is  now  [ilaced 
on  the  base  of  the  machine,  and  the  plunger  cap  placed  firmly  against  it  for  the  perma- 
nent adjustment  of  the  flask.  The  metal  is  now  heated  in  the  recess  prepared  for 
it  and  when  thoroughly  melted  the  casting  is  made  by  packing  moist  asbestos  fiber 


136  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

in  the  plunger  cap  of  the  machine  and  bringing  it  gently,  but  firmly,  against  the  flask. 
When  the  metal  is  cold,  remove  and  cut  away  the  gateways,  leaving  a  small  portion 
remaining  to  help  retain  the  rubber.  The  teeth  are  placed  by  means  of  the  rubber 
attachment. 

The  advantages  of  this  method  over  the  swaged  plate  are  as  follows: 

1.  Better  adaptation,  especially  in  undercut  cases,  as  the  case  is  cast  direct 
on  the  original  model. 

2.  It  is  stronger,  as  a  rim  is  carried  not  only  on  the  outside  edge  of  the  plate 
but  also  on  the  lingual  surface  a  short  distance  from  the  teeth,  the  plate  can  also  be 
varied  in  thickness  according  to  the  strain. 

3.  Better  anchorage  for  the  teeth. 


CASTING  WAX 

By  T.  C.  Trigger,  St.  Thomas,  Ont. 


I  have  been  using  wax  in  various  colors,  and  find  that  a  rose  tint  is  more  trans- 
parent than  the  green,  which  is  a  very  essential  point,  as  the  marginal  edges  of  the 
cavity  can  be  easily  seen  and  the  thickness  of  the  wax  can  be  determined,  over-lapping 
the  marginal  edges.  To  test  the  transparency  of  wax  in  various  colors,  I  made  thin 
slices  of  equal  thickness,  and  found  that  the  rose-colored  transmitted  the  light  more 
than  the  green,  and  the  latter  had  to  be  cut  very  thin  before  any  translucency  could 
be  detected. — Dental  Practice. 


TO  OVERCOME  WEAKNESS  OF  A  CAST  GOLD  BRIDGE 
By  W.  J.  Montgomery,  Chicago,  111. 

The  brittleness  of  a  cast  gold  bridge,  due  to  the  gold  having  been  melted  several 
times,  may  be  overcome  by  sprinkling  mercury  bichloride  over  the  molten  gold 
immediately  before  casting. — Dental  Brief. 


COLLODION  AS  A  SEPARATING  MEDIUM 

B.  L.  Worthley,  Trenton,  Mo.,  recommends  collodion  as  a  separating  medium 
for  plaster  impressions.  A  single  coat,  followed  when  dry  by  a  little  soapstone 
rubbed  over  the  impression,  insures  a  clean  parting  and  a  smooth  cast. — Dental  Brief. 


THE  IMPRESSION  METHOD  FOR  INLAY  WORK 

By  Henry  W.  Gillett,  D.M.D.,  New  York  City 

Since  the  introduction  to  dentists  of  gold  casting  by  Dr.  Taggart,  a  large  part 
of  the  dental  profession  has  been  concentrating  its  energies  on  the  technique  of  the 
casting  process.  As  a  result  many  variations  have  been  evolved  and  published. 
Prior  to  Dr.  Taggart's  introduction  of  the  cast  gold  inlay,  and  antedating  it  by 
a  period  sufficient  for  many  of  us  to  have  adopted  it  for  constant  use  in  filling 
cavities  of  medium  and  large  size,  we  had  the  so-called  matrix,  or   two-piece  inlay. 

When  the  cast  inlay  became  possible,  many  operators  who  had  been  using  the 
matrix  inlay  found  it  easier  to  adapt  to  the  new  process  the  technique  they  were 
already  familiar  with,  than  to  develop  the  technique  devised  and  so  successfully 
carried  out  by  Dr.  Taggart. 

This  so-called  indirect,  or  impression  method,  has  been  repeatedly  shown  at 
clinics,  but  I  think  it  has  not  been  as  carefully  described  in  our  literature  as  it 
deserves  to  be.  Because  of  this  belief,  I  was  easily  persuaded  by  your  committee 
to  endeavor  to  present  the  merits  of  the  process  pursued  by  many  successful 
practitioners,  especially  as  it  gives  me  an  opportunity  to  urge  upon  you  the  need 
for,  and  the  practicability  of  further  advance  in  the  perfection  of  this  branch  of 
our  work. 

In  order  that  we  may  understand  each  other,  I  desire  to  say  at  this  poiht  that 
in  speaking  of  gold  inlays,  or  gold  restorations,  I  have  constantly  in  mind  inlays 
or  restorations  that  fit  the  cavity  margin  accurately  at  all  points,  and  that  repro- 
duce, as  far  as  possible,  the  anatomical  features  of  the  parts  they  replace.  In  my 
estimation  inlays  are  failures  if  they  show  a  cement  line,  lack  approximal  contact, 
or  present  smooth  occlusal  surfaces. 

The  type  of  inlay  I  shall  have  most  in  mind  is  the  ordinary  occluso-approximal 
of  at  least  medium  size,  and  from  this  up  to  complex  restorations  of  whole 
crowns. 

In  order  to  direct  your  attention  at  once  to  the  points  I  desire  to  emphasize, 
I  will  first  enumerate  some  of  the  advantages  which  I  believe  accrue  to  the  user  of 
the  indirect  inlay  method,  and  will  then,  at  the  risk  of  being  tiresome,  endeavor 
to  describe  in  detail  the  steps  of  that  method. 

In  conclusion  I  shall  call  to  your  attention  the  need  for  further  advance  in  our 
technique  with  regard  to  reproduction  of  occlusal  surfaces. 

Among  the  advantages  which  I  personally  find  in  the  indirect  method  are 
the  following: 

First — Superiority  of  fit  and  ability  to  use  an  alloyed,  and  consequently 
harder  gold  without  interfering  with  this  superior  fit.  My  usual  choice  for  inlays 
is  an  alloy  of  971/^%  pure  gold  and  2}/^%  pure  platinum.  In  cases  where 
greater  hardness  is  desired,  a  higher  percentage  of  platinum  may  be  advantageously 
used,  but  the  2^-^%  alloy  presents  the  advantage  of  sufficient  ductility  to  permit 
of  the  manipulation  necessary  to  correct  the  errors  accompanying  the  casting 
process. 


138  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Second — The  fact  that  we  have  in  this  process  a  hard  die  or  cast  of  the  cavity 
on  which  this  necessary  correction  can  be  done. 

Third — The  comfortable  feeling  that  comes  from  the  knowledge  that  if  any- 
thing goes  wrong  in  the  casting  process  itself  where  it  is  less  easy  to  guard  against 
error,  it  is  simple  to  start  afresh  without  recalling  the  patient  since  the  same  die 
and  occlusion  are  at  hand,  and  will  ser\'e  to  make  a  dozen  reproductions,  if  neces- 
sary. 

Fourth — Opportunity  for  more  perfect  carving  of  anatomical  characteristics 
in  complex  cases,  and  opportunity  for  finishing  on  the  die,  relieving  the  patient 
of  all  finishing  in  the  mouth,  except  the  final  burnishing  of  the  margins,  and  the 
slight  polishing  needed  to  remove  the  burnisher  marks,  thus  conserving  the  time 
of  the  patient. 

Fifth — The  removal  to  the  laboratory  bench  of  all  the  carving  and  finishing 
at  the  hands  of  an  assistant,  and  the  consequent  saving  of  the  operator's  time, 
and  the  enlargement  of  his  capacity  to  turn  off  work. 

It  has  been  for  some  years  my  expressed  belief  that  the  same  care  and  atten- 
tion to  detail  by  either  the  direct  or  indirect  process  would  produce  similar  results. 
I  have  more  recently  come  to  feel  that  for  all  work  except  the  conspicuously  simple 
cases,  the  indirect  process  will  average  to  turn  out  better  results;  that,  contrary 
to  the  frequently  expressed  opinion  the  finished  product  is  actually  separated  from 
the  cavity  by  fewer  steps  conducive  to  error  than  when  the  direct  process  is  followed. 

It  is  generally  held  by  advocates  of  the  direcc  process  that  the  indirect  process 
introduces  two  extra  chances  of  error  in  the  taking  of  the  impression  and  the  making 
of  the  die. 

Frequently  we  hear  the  claim  made  that  the  wax  model  exactly  fits  the  cavity, 
and  that  the  gold  casting  reproduces  it  with  absolute  exactness.  Neither  of  these 
statements  is  generally  true  under  the  conditions  necessary  in  our  work. 

The  wax  model  necessarily  changes  in  volume  on  being  transferred  from  the 
temperature  of  the  mouth  to  that  of  the  operating  room  and  again  on  being  in- 
vested, the  investment  expands  in  the  drying,  wax  burning  and  casting  steps  in  a 
ratio  usually  unknown  to  the  workman;  worse  still  it  often  appears  to  warp  in 
directions  to  which  the  workman  has  no  clue  except  as  supplied  by  the  ill  fit  of 
ihe  casting. 

it  is  my  belief  that  the  errors  in  the  taking  of  cavity  impressions  and  those  in 
making  the  die  or  duplicate  of  the  cavity  are  more  easily  within  the  control  of  the 
operator  than  are  those  liable  to  occur  at  nearly  every  other  step  of  the  casting 
process — consequently  I  hold  that  when  those  two  steps  have  been  well  performed 
the  operator  can,  by  the  aid  of  the  resulting  die,  correct  most  of  the  errors  occurring 
in  the  subsequent  steps  and  that  his  product  will  suffer  less  from  errors  influencing 
its  fit.  In  short,  I  contend  that  until  such  devices  as  Taggart's  Wax  Warmer  and 
Van  Horn's  device  for  maintaining  body  temperature  during  investment  are  ob- 
tainable, until  investments  are  better  understood,  and  the  errors  in  their  manipu- 
lation better  guarded  against,  greater  accuracy  of  fit  will  be  possible  by  the  in- 
direct process  than  by  the  direct  process,  assuming  similar  conditions  with  regard 
to  care  and  skill  in  both  instances. 

The  description  of  the  steps  which  I  am  about  to  give  you  will  show  you  that 
there  is  greater  chance  of  controlling  error  due  to  shrinkage  of  the  impression 
material  when  taking  the  cavity  impression  than  there  is  of  controlling  that  of  the 
wax  model  when  made  in  the  cavity  because  it  can  be  better  kept  under  pressure 


THE  IMPRESSION  METHOD  TOR  I  NLA  Y  WORK  139 

and  some  of  its  shrinkage  compensated  for  in  the  earlier  stages  of  its  cooling  by 
forcing  it  further  into  the  cavity.  I  think  it  will  be  conceded  without  much  argu- 
ment that  we  have  amalgams  from  which  dies  may  be  made,  which  reproduce  with 
but  very  slight  error  the  form  indicated  by  the  impression. 

I  will  now  attempt  to  describe  in  detail  the  steps  of  the  process. 

Cavity  Preparation — The  only  special  point  to  note  as  different  from  any  inlay 
cavity  preparation  is  that  in  bell-shaped  teeth  it  facilitates  the  work  to  cut  back 
the  approximal  contour  making  a  flat  approximal  wall.  This  is  not  feasible  in 
many  mesial  cavities,  but  in  distal  cavities  and  others  so  placed  that  it  will  not 
result  in  undue  exposure  of  gold,  it  permits  the  bringing  of  the  approximal  margins 
of  inlays  to  the  area  of  immunity  with  less  sacrifice  of  tooth  tissue  and  with 
less  discomfort  for  the  patient  than  if  the  whole  cavity  is  broadened  to  the  line 
of  safety. 

The  impression  of  a  cavity  so  prepared  is  less  likely  to  be  injured  in  withdrawal. 

The  Bite — The  cavity  being  prepared,  the  next  step  in  my  own  routine  is  to 
get  a  wax  bite  with  sufficient  accuracy  to  permit  placing  the  die  in  it  in  its  correct 
relations  to  the  opposing  and  adjoining  teeth. 

If  the  die  is  inaccurately  placed  then  the  finished  work  will  be  wrong  in  con- 
tour, or  occlusion,  or  both.  Sometimes  I  take  also  a  small  impression  of  opposing 
teeth  from  which  a  cast  is  made  for  setting  into  the  wax  bite,  and  this  is  frequently 
the  more  accurate  procedure,  as  it  usually  provides  a  more  perfect  reproduction 
of  the  opposing  teeth  than  does  the  imprint  in  the  wax. 

In  taking  the  wax  bite,  it  is  preferable  to  select  a  fairly  hard  wax  so  it  will  be 
rigid  when  cold,  and  thus  stand  handling  when  placing  the  die  without  resulting 
distortion.  When  taking  the  bite  place  the  vaselined  fingers  of  one  hand  each  side 
of  the  teeth  containing  the  cavities  so  as  to  prevent  lateral  spreading  of  the  wax, 
and  with  the  fingers  of  the  other  hand  mold  the  wax  first  well  into  the  cavities  and 
then  flatten  it  till  the  depth  of  wax  into  which  the  opposing  teeth  are  to  bite  is 
reduced  to  the  minimum  required  for  the  imprint  of  the  desired  portion  of  those 
teeth.  If  there  is  a  large  surplus  of  wax  it  tends  to  flow  out  laterally  when  the 
patient  closes  the  teeth  and  thus  distorts  the  impression  of  all  the  teeth  included. 
Some  patients  can  materially  assist  by  maintaining  closure  and  molding  the  wax 
against  the  teeth  with  the  tongue  while  the  operator  does  the  same  on  the  buccal 
surface  with  the  fingers.  Sometimes  it  is  well  to  chill  the  wax  before  removal, 
but  usually  the  surplus  is  sufficient  to  permit  of  its  immediate  removal  without 
distortion. 

Taking  the  Impression^Several  materials  are  in  use.  The  writer  prefers  "Per- 
fection Impression  Material"  because  it  softens  at  a  low  temperature,  and  quickly 
becomes  rigid  on  chilling.  There  are  numerous  variations  of  technique  for  getting 
the  impression,  but  underlying  all  the  desirable  ones  are  two  general  principles. 
The  first  is  that  the  impression  material  should  always  be  so  confined  as  to  cause  it 
to  be  pressed  directly  against  all  parts  of  the  cavity,  particularly  all  margins. 
The  second  is  that  the  deeper  part  of  the  body  of  the  material  to  be  used  should  be 
firmer  than  the  surface  so  that  it  shall  serve  as  a  support  to  hold  the  softer  parts  up 
to  their  required  office,  and  as  the  whole  mass  is  being  cooled  under  pressure,  to 
force  the  softer  parts  closer,  if  they  tend  to  contract  away  from  the  surfaces  of 
which  an  accurate  imprint  is  desired. 

This  is  accomplished  in  various  ways.  For  short  root  ends,  or  for  complex 
restorations  where  a  whole  occlusal  surface,  or  more  than  three  surfaces  of  a  tooth 


140 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


are  included  in  the  restoration,  it  is  frequently  desirable  to  fit  a  seamless  band  of 
soft  copper,  or  other  metal,  proceeding  as  if  to  fit  a  crown  band  except  to  have  it  a 
little  looser.  When  this  is  complete  a  block  of  impression  material  is  formed  to  a 
cone  shape,  having  its  tip  just  soft  enough  so  as  to  avoid  stickiness,  and  is  then 
pressed  well  home  with  the  fingers,  and  kept  under  pressure  while  being  cooled  by 
a  stream  of  cold  water,  or  better,  a  stream  of  compressed  air  at  20  to  30  or  more 
pounds'  pressure.  The  latter  plan  is  preferable  to  most  patients  because  less 
irritating  to  other  teeth,  and  it  is  neater. 

With  the  opposite  extreme  in  cavities — the  simple  four-walled  cavity,  just  a 
stick  of  compound  and  an  instrument  to  keep  the  gum  awa^^  if  it  be  needed,  serves 
better  than  any  cup,  as  the  solid  base  of  the  block  of  impression  material  takes  the 
place  of  the  cup,  and  confines  the  softer  portion. 

For  ordinary  occluso-approximal  cavities,  cups  made  of  German  silver, 
platinoid  or  the  Roach  Impression  Cups  are  preferred  by  many,  and  serve  admir- 
ably. In  using  these  cups  it  is  important  that  after  placing  the  material  in  the 
cup  the  whole  mass  be  cooled  and  the  surface  again  softened  so  as  to  provide  for 
the  hard  base  of  material  already  referred  to  as  essential  to  success. 

I  have  left  to  the  last  the  technique  which  I  use  most  frequently,  and  which  I 
consider  best  adapted  to  making  sure  of  a  well  defined  imprint  of  all  parts  of  the 
cavity  margin  of  occluso-approximal  cavities  extending  to,  or  beyond  the  gum  line. 


Fig.  1 

Fig.  1 — Typodont  with  prepared  cavities  and  matri.x  in  position  ready  for 
impression  of  one  cavity. 


Selecting  a  piece  of  platinoid  of  32  or  34  gauge  a  little  narrower  than  the  length  of 
the  crown  of  the  tooth  in  hand,  and  longenough  to  permit  of  its  being  curved  around 
so  as  to  cover  its  lateral  sides  1-3  or  1-2  way,  I  proceed  to  form  a  matrix  by  trimming 
the  cervical  side  so  as  to  impinge  as  little  as  possible  on  the  gum,  and  usually  cut 
the  middle  of  its  occlusal  side  in  a  curve  with  its  depression  in  the  center.  This 
latter  facilitates  forcing  the  impression  material  well  home  as  it  does  not  have  to 
enter  so  deep  a  pocket,  and  the  curving  around  the  sides  of  the  tooth  helps  to  con- 
fine the  material  and  hold  it  to  its  work  at  the  approximal  margins.      (Fig.  l). 

This  matrix  is  generally  held  in  place  with  wedges  of  absorbent  cotton  tucked 
in  between  it  and  the  adjoining  tooth.  If  the  shape  of  the  tooth  containing  the 
cavity  is  such  that  any  bit  of  impression  material  overlapping  beyond  the  cavity 
margin  is  likely  to  be  broken  in  the  removal  of  the  impression,  then  the  matrix 
is  wedged  snugly  against  the  cavity  margin  so  as  to  avoid  having  such  a  surplus. 


THE  IMPRESSION  METHOD  FOR  INLA  Y  WORK  141 

In  this  case  the  cavity  margin  in  the  die  is  formed  by  the  angle  of  junction  of  the 
cavity  wall  and  the  matrix.  If,  on  the  other  hand,  the  tooth  shape  is  such  as  to 
facilitate  removal  of  impression  and  surplus  intact,  the  matrix  is  wedged  less 
firmly  into  place  so  as  to  allow  the  impression  material  to  extend  over  the  cavity 
margin  and  insure  an  imprint  of  the  surface  of  the  tooth  adjacent  to  the  cavity  as 
well  as  that  of  the  margin  itself. 

The  matrix  being  satisfactorily  placed,  a  piece  of  impression  material  of  appro- 
priate size  and  shape  is  selected,  and  one  end  of  it  warmed  and  formed  into  a  cone 
shape.  The  cone  may  advantageously  have  been  formed  in  advance  by  assistants, 
thus  conserving  the  operator's  time.  When  softening  and  shaping  the  material, 
it  is  helpful  to  keep  the  fingers  lightly  coated  with  vaseline.  Having  the  cone  of 
compound  softened  with  regard  to  its  tip,  and  firm  in  its  deeper  parts,  warm  the 
outer  surface  of  its  base  enough  so  the  corners  will  not  interfere  with  exerting  firm 
pressure  with  the  thumbs,  or  fingers.  Oftentimes  I  then  stick  the  base  while  thus 
superficially  softened  onto  whichever  thumb  or  finger  is  the  appropriate  one  for 
the  case,  and  so  carry  it  to  position,  pressing  it  firmly  to  place  and  guiding  or  sup- 
porting it  with  other  fingers  as  may  be  necessary.  Sometimes  this  forming  of  the 
surplus  with  the  fingers  is  necessary  in  order  to  insure  removal  of  the  matrix  with 
the  impression.     I  keep  pressure  on  the  mass,  and  direct  a  stream  of  compressed 


Fig.  2  Fig.  3  Fig.  4 

Fig.  2 — Impression  of  cavity  witli  matrix  in  place. 

Fig.  3 — Section  of  impression  and  plaster  investment  as  it  would  stand  when  ready 

for  packing  die. 
Fig.  4 — Section  of  a  packed  die  before  removing  impression  and  investment. 

air  against  the  material,  thus  quickly  chilling  it.  If  the  cotton  wedges  are 
accessible  I  usually  remove  them  before  unseating  the  impression.  This  is  not 
essential,  but  sometimes  facilitates  removal  of  the  impression  without  liability  to 
fracture  of  important  parts. 

After  the  removal  I  immediately  dry  the  impression  with  a  stream  of  cold  air, 
and  examine  it  carefully  with  a  magnifying  glass  to  make  sure  that  the  imprint  of 
the  whole  cavity  and  especially  of  the  cavity  margin  is  clear  and  accurate.  (Fig. 2). 

The  patient  is  then  dismissed,  and  the  tray  containing  the  impression,  bite 
and  card  bearing  the  necessary  instructions  is  sent  to  the  laboratory.  If  there  are 
no  unusual  conditions,  I  give  the  case  no  further  thought  until  the  patient  arrives 
for  the  next  appointment,  at  which  time  the  inla}'  is  tried  in,  its  approximal  and 
occlusal  relations  tested  and  perfected,  if  necessary,  and  it  is  cemented  in  place. 

In  the  laboratory  the  first  step  on  receiving  the  tray  is  to  inspect  the  relations 
of  the  matrix  to  the  cavity  margin.  If  it  has  sprung  away  at  all  it  is  pressed  ac- 
curately to  place,  a  very  little  stick  wax  applied  to  its  exposed  side,  and  a  bit  of 
match  stuck  to  it,  the  other  end  of  the  match  being  firmly  imbedded  in  wax. 
This  provides  a  brace  that  holds  the  matrix  in  place,  and  avoids  risk  of  distorting 


142  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

the  impression,  which  would  invariably  follow  if  enough  hot  wax  to  hold  the  matrix 
were  to  be  applied  directly  to  it  while  under  pressure  sufficient  to  retain  it  in 
position.  The  hot  wax  would  soften  the  material  on  the  other  side  of  the  matrix, 
and  cause  it  to  yield  under  the  pressure.  Numerous  other  ways  may  be  equally 
satisfactory,  but  this  one  is  efficient  and  simple. 

In  the  case  of  double  compound  cavities  with  two  matrices  in  the  impression 
a  ring  of  stiff  wire  slit  on  one  side  may  be  opened  enough  so  as  to  exert  the  correct 
amount  of  pressure  when  its  ends  are  applied  to  the  matrices,  and  a  minimum  of 
wax  added  at  the  point  of  contact. 

Investment  of  Impression — The  matrix  being  secure  a  quantity  of  plaster  is 
mixed  and  at  the  moment  when  still  soft  enough  to  permit  of  so  doing,  and  yet 
not  so  soft  as  to  flow  in  and  cover  it,  the  block  of  impression  material  and  matrix 
is  pressed  straight  down  into  the  plaster  in  such  a  manner  as  to  leave  the  impression 
exposed  at  the  bottom  of  the  opening  in  the  plaster  made  by  the  passage  of  the 
mass  down  through  it.  Careful  examination  is  now  made  to  see  that  no  part  of  the 
impression  is  covered  with  plaster,  and  any  irregularity  in  the  sides  of  the  hole 
or  pit  is  filled  in  so  as  to  avoid  needless  surplus  in  the  die. 

The  result  is  a  plaster  block  encasing  the  mass  of  impression  material,  except 
with  regard  to  the  surface  bearing  the  imprint  of  the  cavity,  which  lies  exposed  at 
the  bottom  of  a  hole  of  a  depth  equal  to  that  desired  for  the  die,  and  of  a  diameter 
approximating  that  of  the  crown  of  the  tooth  involved.  (Fig. 3).  As  soon  as  the 
plaster  has  set  the  die  may  be  packed. 

Packing  the  Die — The  hole  in  the  plaster  as  described  is  the  mold  into  which 
amalgam  is  to  be  packed  to  form  the  die.  Select  anj'  good  amalgam  in  sufficient 
quantity,  and  reduce  it  to  a  smooth  plastic  mass,  such  as  is  obtained  by  encasing 
the  mass  resulting  from  triturating  in  a  mortar  in  a  sheet  of  rubber  dam  and  gather- 
ing the  rubber  tightly  around  it;  or  by  dropping  it  into  a  rubber  finger  cot,  and 
gripping  that  closely  around  the  mass,  and  rubbing  the  resulting  knob  vigorously 
against  the  palm  of  the  other  hand.  From  the  soft  plastic  mass  thus  obtained  take 
a  small  portion  and  with  rounded  points  and  burnishers  of  such  size  as  are  adapted 
to  the  impression  in  hand  work  it  carefully  onto  the  surface  of  the  impression, 
placing  it  definitely  into  all  inequalities  and  small  depressions. 

As  the  surface  of  the  impression  becornes  covered,  larger  amalgam  masses 
may  be  used.  Finally  mallet  force  on  a  stick,  which  nearly  closes  the  opening, 
heavy  pressure  with  the  thumbs,  or  with  a  clamp  and  rubber  block  may  be  used  to 
consolidate  the  mass  and  expel  surplus  mercury.  (Fig.  4).  This  work  may  be  con- 
veniently done  late  in  the  day  and  the  amalgam  allowed  to  set  over  night,  but  by 
using  a  quick  setting  amalgam  the  time  may  be  shortened.  When  the  die  is 
removed  from  the  impression,  imperfections,  if  an}-,  and  surplus  near  the  margins 
are  carefully  removed,  and  the  sides  of  the  base  are  given  a  slightly  tapering 
shape  away  from  the  occlusal  surface  to  facilitate  seating  and  removal  from  the 
plaster  cast.  Usually  if  one  or  more  dies  are  to  be  seated  in  the  same  cast,  or 
if  the  base  of  the  die  is  of  a  regular  shape,  a  groove  is  cut  across  its  bottom  so  as 
to  indicate  its  seat  in  the  cast,  when  working  on  it  at  a  later  stage,  without 
need  for  trial. 

The  finished  die  is  then  carefully  seated  in  the  wax  bite.  In  doing  this  observe 
any  portions  of  wax  that  interfere,  and  trim  them  away  until  the  die  is  accurately 
seated,  depending  upon  the  fit  of  such  portions  of  the  die  as  you  know  to  be  accurate 
for   your    guide    on    this   point,   and   ignoring  all   parts   where  surplus  has  been 


THE  IMPRESSION  METHOD  FOR  I  NLA  V  WORK 


143 


removed.  Having  seated  the  die  and  waxed  it  to  place,  select  an  articulator, 
preferably  one  provided  with  a  lateral  as  well  as  a  vertical  hinge  movement,  and 
filling  with  plaster  the  portions  of  the  wax  bite  on  the  side  containing  the  die, 
mount  it  in  the  usual  manner.  If  the  imprint  in  the  wax  is  to  be  used  for  repro- 
ducing the  opposing  teeth,  that  may  be  filled  also  and  the  mounting  completed 
from  the  single  mix  of  plaster.  If  a  cast  made  from  a  separate  impression  is  to  be 
used  it  may  sometimes  be  seated  in  the  wax  bite  at  the  same  time  with^the  die 


Fig.  5 
Fig.  5 — Dies  mounted  in  casts  on  articulator.     One  die  lifted  out  to  sliow  its  shape. 


or  it  may  be  seated  after  the  cast  containing  the  die  is  run  and  mounted  on  the 
articulator,  and  then  attached  to  its  articulator  arm.  When  the  wax  has  been 
removed,  and  the  surplus  plaster  dressed  away,  the  result  is  a  replica  (Fig.  5)  of  the 
conditions  in  the  mouth  that  permits  of  free  manipulation  in  carving  the  wax  dupli- 
cate with  no  hindrance  from  tongue,  cheeks,  saliva,  overlapping  and  bleeding  gums, 
poor  light,  difficult  access  and  nervous  patient.   The  wax  may  be  pressed  into  place 


Fig.  6 
Fis.  6— Example  of  pronounced  cusp  carving  with  round  bottomed  defective'sulci. 


144  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

with  the  aid  of  a  matrix,  and  held  under  pressure  until  chilled,  the  die  may  be  lifted 
out  and  all  margins  exposed  to  close  scrutiny  under  direct  light,  the  carving 
may  proceed  under  the  most  favorable  conditions,  and  at  the  hands  of  an  assist- 
ant, who  can,  with  training  and  practice,  easily  produce  results  in  that  particular 
line  that  excel  in  perfection  the  work  of  the  average  practitioner.  For  this  branch 
of  the  work  young  women  often  prove  very  valuable  assistants. 

The  carving  being  complete,  the  process  of  casting  does  not  vary  from  that 
to  be  pursued  in  any  casting,  but  when  that  step  is  completed  the  casting  is  tried 
in  the  die,  all  imperfections  interfering  with  seating  carefully  noted,  and  removed, 
and  the  rough  finishing  performed  first,  then  with  burnisher  and  stone  the  margins 
are  fitted  with  careful  exactness,  and  finally  the  inlay,  or  restoration,  is  polished 
ready  for  insertion. 

If  the  impression  has  been  accurately  taken,  the  die  accurately  made  and 
accurately  seated,  the  resulting  inlay  should  go  to  place  without  any  manipulation, 
and  need  only  to  be  set  in  cement.  If  the  contour  or  occlusion  are  not  exactly 
right,  it  is  very  easy,  having  the  die  at  hand,  to  place  it  in  that  and  grind  and  polish 
as  desired.  The  absence  of  grinding  in  the  mouth  is  highly  appreciated  by  most 
patients.  For  doing  the  polishing,  wheels  made  from  ordinary  typewriter,  or 
ink  erasing  rubber  will  be  found  most  efficient.  The  ordinary  round  typewriter 
eraser,  costing  four  cents,  will  make  four  wheels  five-eighths  of  an  inch  in  diameter, 
and  when  once  used  they  become  an  indispensable  adjunct  in  this  work. 

In  complex  restorations,  where  the  whole  top  of  a  tooth  is  to  be  restored,  the 
indirect  process  reaches  its  fullest  fruition. 

It  is  a  great  satisfaction  to  be  able  to  remove  a  gold  shell  crown,  whose  fit 
is  such  that  "sloppy"  is  a  mild  term  for  describing  it,  and  on  finding  that  the 
previous  shaping  has  left  the  lateral  sides  intact,  to  replace  it  with  a  hollow  case 
restoration  supplying  perfectly  every  requirement  of  a  useful  tooth  and  every 
mechanical  requirement  as  to  support  without  the  need  of  a  band  encircling  the 
root,  to  foster  uncleanliness  at  the  gum  margin. 

The  men  who  can  do  in  the  mouth  the  required  carving  for  such  a  case  are 
exceedingly  rare,  and  when  such  a  carving  has  been  completed,  with  the  expendi- 
ture of  much  effort  and  patience,  the  risk  of  a  slight  mishap  spoiling  it,  and  the 
difficulties  of  perfecting  its  fit  in  the  mouth  after  it  is  cast,  are  considered,  it  is 
removed  from  the  list  of  feasible  operations. 

With  the  indirect  process,  however,  such  a  restoration  becomes  almost  as 
readily  feasible  as  the  filling  of  an  ordinary  cavity,  and  the  perfection  of  fit  and 
contour  are  sources  of  much  satisfaction. 

For  complex  restorations  I  frequently  cast  first  a  24-karat  base  (Fig.  9)  and  fit 
it  to  the  die,  and  then  cast  on  it  the  desired  platinized  alloy.  This  results  in  a  very 
perfectly  fitting  restoration  since  the  pure  gold  base  is  easily  manipulated  on  the 
die,  and  any  desired  degree  of  hardness  is  obtainable  with  the  alloyed  gold  used  for 
the  rest  of  the  casting.  Usually  my  laboratory  associate  prefers  to  cast  this 
platinized  top  separately,  having  formed  the  wax  over  the  pure  gold  base  in  its 
seat  on  the  die,  and  after  so  casting  the  top  to  solder  the  two  together.  (Fig.  10).  In 
that  case  he  uses  one  of  the  well  known  solders  for  which  the  formula  has  been 
given  us  by  Dr.  Fred  A.  Peeso.  This  solder  matches  so  perfectly  the  color  of  a 
2H%  platinum  alloy  that  when  used  to  add  a  contact  point,  for  instance,  it  can 
not  be  detected,  after  being  well  polished. 


THE  IMPRESSION  METHOD  FOR  I  NLA  Y  WORK 


145 


Fig.  7  (a) 


Fip.  7  (b) 

Fig.  7 — Cast  from  an  orthodontia  case  of  Dr.  J.  Lowe  Young's   showing  uoinial  rendition  (a) 
and  condition  after  inlays  were  inserted  a  few  years  later. 


146 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


As  this  solder  is  so  readily  made,  and  so  serviceable,  I  give  the  formula  here 
for  the  benefit  of  those  not  familiar  with  it; 

Coin  gold,  20k.  solder;  equal  parts;  fuse  thoroughly  on  charcoal  block  and 
roll  thin. 

The  melting  point  of  the  solder  is  high  enough  so  ordinary  22  k.  solder  may 
readily  be  flowed  on  it.  .   ' 

Such  complex  restorations  are  of  great  service  in  restoring  badly  broken  down 
molars,  and  with  the  addition  of  dowel  pins  they  are  frequently  most  serviceable 
as  bridge  abutments. 

These  steps  seem  long  in  the  description,  but  if  proper  assistance  is  at  hand, 
the  process,  as  described,  can  be  made  to  conserve  the  operator's  time  and  enlarge 
his  earning  capacit)'.  Intelligent  young  women  make  very  satisfactory  assist- 
ants for  this  work,  and  there  is  no  part  of  it  that  they  can  not  readily  learn  to 
perform. 

It  remains  to  be  stated  that  in  the  case  of  the  practitioner  who  does  all  this 
work  with  his  own  hands,  there  is  doubt  as  to  his  turning  out  as  much  work  by 
following  the  steps  as  described  as  by  the  direct  process,  but  it  is  my  belief  that 
he  will  turn  out  work  that  will  be  of  greater  service  to  his  patients.  If  that  same 
practitioner  will,  however,  take  the  needful  time  to  train  an  assistant  to  do  the 
routine  steps  that  go  on  at  the  laboratory  bench,  he  will  find  a  material  increase 
in  his  efficiency. 


Fig.  8  (a) 


Fig.  8  (b) 


Fig.  S  (a) 


Fig.  8  (a) 


Fig.  8  (b) 


Fig.  8  (b) 


Fig.  8  (b) 


Fig.  8 — Illustrations  of  defective  (a)  and  good  (b)  occliisa)  surface  carving  by  courtesy 
Dr.  J.  Lowe  Young  and  Tire  Journal  of  the  Allied  Societies. 


I  now  desire  to  call  your  attention  to  the  need  for  further  development  of  our 
technique  in  the  matter  of  restoration  of  the  anatomical  features  of  occlusal 
surfaces.  All  the  previous  generations  of  dentists  have  been  working  by  methods 
that  did  not  permit,  within  the  bounds  of  reasonable  effort  on  the  part  of  the 
operator,  or  of  reasonable  endurance  on  the  part  of  the  patient,  of  restoration  of 
the  sulci,  ridges,  pits  and  grooves  of  occlusal  surfaces,  and  even  the  restoration 
of  cusps  was  more  often  than  not  necessarily  omitted.  The  resulting  even-sur- 
faced fillings  served  ordinarily  to  preserve  the  teeth,  but  not  to  preserve  their  full 


THE  IMPRESSION  METHOD  FOR  I  NLA  Y  WORK  147 

function.  Those  of  you  who  do  orthodontia  realize  the  imperative  need  for  cusp 
restoration,  and  I  doubt  not  that  some  of  you  have  been  asked  why  teeth  with 
large  fillings  served  so  poorly  as  masticators. 

At  this  point,  with  your  permission,  I  desire  to  quote  a  few  sentences  from  an 
unpublished  paper  by  Dr.  J.  Lowe  Young,  read  before  the  Academy  of  Dental 
Science,  and  to  be  published  in  "The  Journal  of  the  Allied  Societies :"* 

"Did  it  ever  occur  to  you  that  the  orthodontist  often  works  for  years 
to  build  up  this  normal  occlusion,  only  to  have  it  pulled  down  in  a  day  by 
ruthless  extraction  of  a  single  tooth,  or  by  the  lack  of  restoration,  by  the 
general  practitioner,  of  cusp  contour  or  approximal  contact  in  making 
fillings  or  inlays? 

"It  would  seem,  therefore,  that  the  dentist  must  share  the  responsi- 
bility of  the  orthodontist  in  emphasizing  the  importance  of  normal 
occlusion  by  preserving  it  at  all  times,  and  at  least  by  not  destroying  it. 

"Hence,  if  the  general  practitioner  is  to  properly  restore  any  part 
of  the  dental  apparatus,  he,  like  the  orthodontist,  must  have  in  his  mind's 
eye  the  forms,  surfaces  and  positions  of  the  dental  organs  when  normal. 

"The  value  of  proximate  contact,  the  proper  occlusion  of  each 
cusp,  the  size  of  each  fossa,  and  the  direction  of  each  sulcus,  should  be 
known  to  him  who  aspires  to  restore  or  re-create  these  anatomical 
forms." 

For  a  time  after  the  introduction  of  the  cast  inlay  we  were  fully  occupied  in 
coping  with  the  difificulties  of  technique,  and  the  problems  of  marginal  fit  and 
anchorage.     Now  that  these  have  become  so  well  understood  it  behooves  us  to 


Fig.  9 

Fig.  9  — Die  and  24K  base  for  complex  restoration    of  molar  with  over-lap  ready  to 

be  fitted  to  the  die. 
Fig.  10 — Die,  24K  base,  and  a  2]/^  per  cent  platinized  cast  cusps  for  comple.x  molar 
restoration,  the  two  latter  ready  for  soldering  together. 

consider  the  fact  that  the  casting  process  enables  us  to  carve  accurate  reproductions 
of  any  tooth  surface  with  but  little  extra  expenditure  of  time,  and  to  restore 
broken  down  tooth  surfaces  in  a  manner  that  shall  leave  them  very  close  to  normal 
in  efficiency. 

I  confess,  with  regret,  that  my  own  development  in  this  line  has  been  slow, 
and  I  look  back  with  sorrow  to  large  occlusal  inlays  only  two  years  old  because 
they  were  finished  in  the  sweeping  curves  of  our  earlier  technique. 

Later  on  I  reached  the  point  of  full  cusp  and  sulcus  reproduction  (Fig.  6)  and 
realized  that  this  meant  progress,  but  cases  that  satisfied  me  six  months  ago  1  now 
regard  with  regret  because  they  were  so  carved  that  the  bottoms  of  the  sulci  could 

♦Note. — See  June  1912,  The  Journal  of  the  Allied  Societies. 


148  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

be  polished,  and  this  meant  absence  of  the  grooves  and  pits  that  belong  there, 
and  which  play  an  important  part  in  the  mastication  of  food. 

The  cusps  of  opposing  teeth  should  never  reach  the  bottoms  of  sulci.  If  they 
do,  there  is  much  greater  risk  of  splitting  the  tooth,  and  the  absence  of  sharp 
grooves  at  the  bottoms  of  the  sulci  mean  lessened  masticating  efificiency.  Com- 
pare Fig.  7  (a)  and  Fig.  7(b),  also  Fig.  8  (a)  and  Fig.  8  (b).  Since  we  are  now 
readily  able  to  supply  them,  there  is  no  longer  a  legitimate  excuse  for  the  absence 
of  sulci,  ridges,  fossae,  grooves  and  inclined  planes  from  the  occlusal  surfaces  of 
our  inlays  and  restorations. 

They  may  be  carved  into  the  wax  surfaces  with  appropriate  instruments,  and 
gravers  and  burnishers  of  similar  shape  may  be  used  for  finishing  if  necessary, 
but  such  a  surface  as  is  left  by  the  casting  process,  when  carefully  performed, 
with  the  anatomical  features  preserved,  is  of  greater  service  to  our  patients  than 
polished  surfaces  with  those  features  absent. 

A  realization  of  this  fact  and  the  logical  action  on  our  part  means  that  in  the 
future  a  filled  tooth  will  be  as  useful  in  performance  of  function  as  a  sound  tooth, 
and  that  our  work  will  have  mounted  to  a  higher  plane  of  usefulness  to  the  world. 


THE  CAST  GOLD  INLAY 

By  C.  G.  Myers,  D.D.S.,  Cleveland,  Ohio. 

At  a  dental  meeting  held  in  Texas  several  years  ago,  a  dentist,  in  paying  a  high 
compliment  to  another  dentist  of  some  local  reputation,  said  that  he  could  mallet 
gold  better  than  any  man  he  ever  knew.  Though  I  cannot  reproduce  the  word 
mallet  in  the  southern  accent  of  this  dentist,  this  expression  had  at  the  time  a  very 
peculiar  effect  on  me  and  I  have  remembered  it  very  vividly  ever  since. 

At  this  time  I  had  been  in  the  practice  of  dentistry  but  a  short  period  and  my 
ideals  had  been  barely  established.  But  it  occurred  to  me  at  the  time  that  if  a  man's 
ability  to  mallet  small  pieces  of  gold  into  a  cavity  of  a  tooth,  and  the  necessary  en- 
durance to  accomplish  certain  results  along  these  lines  constituted  a  great  man  in 
any  profession,  my  ideals  would  have  to  be  very  greatlj'  altered. 

My  experience,  after  a  number  of  years  in  the  practice  of  dentistry,  has  been  that 
dentistry  has  meant  the  carrying  out  of  too  many  minor  and  petty  details  so  as  to 
test  to  the  utmost  one's  nervous  and  physical  powers.  We  find  that  the  productive 
life  of  a  dentist  is  not  so  greac  as  that  of  men  in  other  lines  of  business  and  profes- 
sions, and  this  is  wholly  due  to  the  fact  that  a  dentist  is  subject  to  little  petty  annoy- 
ances and  details  that  have  been  wholly  eliminated  in  other  businesses. 

When  I  attended  dental  college  I  was  taught  that  the  ideal  point  for  condensing 
cohesive  gold  was  the  needle  point  and  that  the  serrated  point  was  simply  an  aggre- 
gation of  needle  points.  We  were  taught  at  that  time  to  use  points  with  deep  serra- 
tions. We  were  also  taught  to  use  gold  in  very  minute  particles.  A  mallet  weighing 
eight  to  ten  ounces  was  used  in  condensing  these  small  particles  of  gold. 

About  this  time  I  learned  the  use  of  non-cohesive  or  soft  foil.  This  gold  is 
manipulated  with  hand  pressure  and  by  the  wedging  process.  Some  men  were  very 
expert  in  the  use  of  this  form  of  gold  and  it  not  only  saved  teeth  successfully,  but  it 
was  also  a  great  time  saver  in  certain  classes  of  cavities. 

After  using  deeply  serrated  points  for  several  3'ears  those  of  shallower  serrations 
came  into  use. 

About  seventeen  or  eighteen  years  ago  it  occurred  to  me  that  if  gold  had  the 
property  of  cohesion,  this  property  was  not  increased  by  the  use  of  serrated  points, 
and  I  designed  and  used  and  continued  to  use  for  twelve  years  a  perfectly  smooth 
point  for  filling  teeth  with  cohesive  gold.  In  facc,  I  used  these  smooth  points  for 
seven  years  before  anyone  was  found  who  filled  teeth  in  this  same  way.  It  was  only 
after  a  paper  had  been  prepared  on  this  subject  for  the  Ohio  State  Dental  meeting 
at  Columbus,  some  years  ago,  that  the  discovery  was  made  that  the  use  of  smooth 
points  had  been  advocated  by  some  dentist  twenty  years  before  and  this  was  abso- 
lutely all  that  could  be  found  in  dental  literature  on  the  subject  up  to  that  time. 
At  the  meeting  at  which  this  paper  was  to  be  presented  there  was  in  attendance  Dr. 
Bowman,  of  Columbus,  and  Dr.  Heise,  of  Cincinnati,  who  were  using  smooth  points 
exclusively  in  manipulating  cohesive  gold,  and  strange  to  say,  from  that  time  to  this 
I  have  found  no  one  pursuing  this  same  line  of  practice. 


150  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

In  filling  some  inaccessible  cavities  with  the  smooth  point  it  was  my  practice 
to  burnish  certain  pieces  of  gold  to  the  mass  of  filling  and  this  in  time  became  my 
practice  throughout  the  entire  filling. 

A  double-end  amalgam  instrument  was  converted  into  a  burnishing  instrument 
and  all  my  fillings  were  introduced  into  the  cavity  by  the  burnishing  process  and  with- 
out the  use  of  the  mallet. 

By  the  use  of  any  of  the  above  methods  a  great  number  of  details  had  to  be 
perfectly  carried  out,  for  the  slightest  imperfection  in  almost  any  part  of  the  work 
meant  an  imperfect  whole. 

At  a  meeting  of  the  Northern  Ohio  Dental  Society,  held  in  Cleveland  shortly 
after  the  discovery  of  the  casting  process  by  Dr.  Taggart,  Dr.  Goslee,  of  Chicago, 
read  a  very  interesting  paper  on  this  subject  and  presented  some  beautiful  specimens 
of  work. 

The  interest  of  the  dentist,  not  only  here,  but  all  over  the  world,  was  aroused 
by  this  wonderful  discovery.  To  show  to  what  an  extent  dentists  were  interested 
in  this  process  it  is  only  necessary  to  state  that  within  a  very  short  time,  after  Dr. 
Taggart  had  given  this  process  to  the  profession,  more  than  three  hundred  applica- 
tions for  patents  on  casting  appliances  were  filed  in  the  patent  office.  Personally, 
nothing  in  dentistry  ever  appealed  to  me  so  strongly  as  did  this  process  of  Dr.  Tag- 
gart's.  As  it  appeared  to  be  the  emancipation  proclamation,  not  only  to  myself 
but  to  all  dentists,  inasmuch  as  it  eliminated  detail  and  filling  of  tooth  cavities. 
In  a  crude  way  this  method  was  adopted  in  my  practice  and  from  that  day  to  this  I 
cannot  recall  a  single  instance  where  I  have  used  gold  in  filling  teeth  by  any  of  the 
older  methods.  And  were  I  compelled  to  again  resort  to  the  practice  of  placing  gold 
in  cavities  as  we  have  been  compelled  to  do  in  years  past,  filling  teeth  would  be  the 
last  business  that  would  appeal  to  me. 

Modern  methods  in  all  lines  of  business,  professions  and  trades  have  eliminated 
detail,  but  up  to  the  past  few  years  it  was  not  thought  possible  to  apply  these  modern 
methods  to  dentistry,  but  with  the  advent  of  cast  gold,  as  suggested  by  Dr.  Taggart, 
we  have  applied  the  process  of  elimination  to  our  own  profession. 

Like  all  other  innovations,  cast  gold  fillings  must  run  the  gauntlet  of  the  skeptic 
and  the  knocker.  About  the  time  that  I  took  up  the  practice  of  dentistry,  crown 
and  bridge  work  was  just  coming  into  use  and  how  it  survived  the  many  knocks  it 
received  at  that  time  is  more  than  can  be  figured  out.  It  was  claimed  that  it  was 
unsanitary,  unsightly  and  that  the  life  of  it  was  very  limited.  It  was  only  when  a 
dentist  found  his  practice  drifting  away  from  him  that  he  began  to  retract  some  of 
the  harsh  things  he  had  said  about  it  and  added  it  as  one  of  the  means  of  extracting 
a  livelihood  from  his  profession.  The  same  will  be  true  of  the  cast  gold  inlay  as  was 
true  of  crown  and  bridge  work.  Some  few  will  make  a  success  of  it  and  others  will 
not  because  it  is  an  apparently  easy  process. 

The  process  is  in  its  infancy,  and  the  appliances  are  crude,  as  compared  to  what 
we  will  have  in  the  future.  Mistakes  will  be  made,  but  through  these  mistakes 
will  come  ultimate  success. 

Let  us  look  at  some  of  the  features  of  elimination  brought  about  by  this  work. 
If  it  had  nothing  to  recommend  it  beyond  the  fact  that  the  teeth  did  not  need  separa- 
tion, which  I  know  from  personal  experience  is  a  barbarous  practice,  it  would  need 
nothing  more  than  this  to  class  it  as  an  ideal  method  of  restoring  lost  contours  in 
teeth.     If  it  has  eliminated  the  rubber  dam,  this  alone  would  recommend  it  to  the 


THE  CAST  GOLD  INLAY  151 

helpless  victim  whose  sufferings  in  the  application  of  this  necessary  adjunct  to  the 
old  methods  of  filling  teeth  were  only  equaled  by  the  tortures  of  the  inquisition. 

Who  has  not  suffered  from  the  application  of  ligatures?  Who  has  not  suffered 
from  having  a  sore  tooth  malleted  upon  until  every  blow  seemed  worse  than  the 
one  previous  and  then  the  final  tortures  of  the  disks,  stones  and  strips  in  the  finishing 
process  until  dentist  and  patient  were  about  as  nearly  nervous  wrecks  as  they  pos- 
sibly could  be  ? 

No  wonder  dentistry  and  the  dentist  have  been  avoided.  Even  the  dentist 
avoids  the  dentist.  You  will  find  in  the  mouths  of  dentists  as  bad  a  state  of  affairs 
existing  as  j^ou  will  find  in  an  equal  number  of  patients.  But  a  different  state  of 
affairs  should  exist  today,  through  the  methods  we  have  of  eliminating  the  sensation 
in  the  tooth  and  all  of  the  disagreeable  features  formerly  connected  with  the  malleting 
of  fillings  in  the  teeth. 

It  will  be  but  a  short  time  when  the  demands  of  the  patient  will  compel  us  all 
to  use  more  humane  methods  in  our  work.  The  physician  today  who  would  attempt 
even  minor  operations  without  the  use  of  some  anesthetic  would  be  classed  as  a 
butcher. 

In  regard  to  the  technique  I  will  have  very  little  to  say.  As  I  said  before,  it 
is  my  impression  that  we  have  only  a  slight  knowledge  of  the  possibilities  of  this 
work  and  our  methods  up  to  the  present  time  are  very  crude.  I  feel  that  Dr.  Price 
with  his  pressure  gauges  and  heat  gauges  is  on  the  right  track  when  it  comes  to 
getting  perfect  and  uniform  results. 

Up  to  the  time  the  cast  inlay  was  introduced,  large  restorations  of  the  tooth  were 
very  frequently  made  with  amalgam  or  crowning.  But  it  is  now  possible  to  save 
teeth  in  a  way  that  crowning  has  to  be  resorted  to  only  on  rare  occasions.  As  at- 
tachments for  bridges  where  at  one  time  extensive  grinding  of  tooth  structure  was 
necessary  or  gold  was  unnecessarily  displayed,  we  can  now  use  gold  inlays  and  gold 
overlays  with  pins  running  into  the  root  canals  as  attachments  for  practically  all 
bridges,  and  the  resulting  work  is  not  only  practical  but  substantial  and  beautiful. 

For  a  great  many  years  all-gold  crowns  made  by  me  were  made  after  the  method 
suggested  by  Dr.  J.  Rollo  Knapp,  of  New  Orleans.  The  results  obtained  by  this 
method  were  perfect  for  this  class  of  work,  but  the  number  of  details  to  be  carried 
out  was  enough  to  discourage  almost  any  beginner  in  this  work.  The  same  results 
or  better  results  are  now  obtained  through  our  knowledge  of  casting  and  with  no 
more  details  than  was  required  in  the  old  shell  crown.  The  construction  of  bridges 
both  gold  and  porcelain  at  one  time  meant  a  multitude  of  details  in  its  construction, 
but  now  with  a  few  simple  fittings  a  bridge  constructed  in  wax  with  porcelain  facings 
in  place,  a  bridge  of  any  size  can  be  made  in  one  casting  and  we  have  never  made  such 
perfect  fitting  plates  as  we  have  made  by  the  casting  process. 

My  method  of  making  inlays  consists  in  making  a  wax  pattern  of  whatever  is 
to  be  reproduced,  investing  this  in  one  of  the  different  investing  compounds  furnished 
by  the  dental  supply  houses,  and  using  either  centrifugal  force  or  the  vacuum  for 
forcing  the  gold  into  the  matrix.  In  casting  directly  on  porcelain  there  is  no  more 
danger  of  checking  the  porcelain  than  there  was  by  the  use  of  the  blow-pipe.  It  is 
only  necessary  that  the  temperature  of  the  investment  and  porcelain  be  raised  to  the 
fusing  point  of  the  gold. 

There  are  only  two  ways  that  the  busy  dentist  can  increase  the  income  derived 
from  his  practice,  one  is  by  increasing  his  fees  and  the  other  by  increasing  his  output 


152  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

of  work.  It  is  very  hard  for  a  dentist  with  an  established  practice  in  a  certain  locality 
to  very  greatly  increase  his  fees,  but  it  is  easily  possible  for  him  to  more  than  double 
the  amount  of  work  turned  out  by  using  the  casting  process. 

Now,  I  feel  grateful  to  anyone  who  will  put  money  in  my  pocket,  and  I  feel 
doubly  grateful  to  anyone  who  will  make  my  business  cares  lighter.  I  do  not  feel 
that  it  would  be  fitting  to  close  this  paper  without  expressing  my  gratitude  to  Dr. 
Taggart  for  all  that  the  casting  process  has  meant  to  me  in  the  last  few  years.  If  I 
am  to  continue  in  the  practice  of  dentistry  I  can  do  so  a  greater  number  of  years  and 
with  greater  profits  each  year  than  I  could  possibly  have  done  under  former  methods. 
Dr.  Taggart  is  an  originator  and  inventor  and  whereas  he  would  like  some  substantial 
returns  as  a  result  of  his  inventions,  for  the  inventor  is  usually  an  erratic  individual 
and  not  a  good  business  man,  he  would  be  more  touched  and  pleased  by  the  generous 
praise  and  plaudits  of  those  in  his  own  profession.  It  is  not  for  me  to  say  whether 
he  is  right  in  obtaining  patents  and  trying  to  enforce  legally  what  the  law  says  is 
due  him,  but  I  do  know  that  the  dentists  have  made  a  very  poor  show  of  appreciation 
for  the  many  benefits  they  have  derived  from  what  Dr.  Taggart  has  taught  them. 
Whether  casting  was  known  to  the  Egyptians  or  Phoenicians  cuts  no  figure  in  this 
case.  Dr.  Taggart  taught  you  what  you  know  about  this  process  and  the  chances 
are  if  it  had  not  been  for  the  energy,  the  sleepless  nights  and  the  outlay  of  money  that 
Dr.  Taggart  has  put  in  this  work,  we  all  would  be  plodding  along  in  the  same  old  rut. 

DISCUSSION 

Dr.  L.  E.  Custer:  Dr.  Myers,  after  reviewing  the  malleted  filling,  first  says  it  is  quite  unnecessary 
to  separate  the  teeth  for  an  inlay.  This  is  true  in  all  proximal  fillings  in  teeth  in  normal  position.  That 
which  was  heretofore  so  hard  to  do  is  now  one  of  the  easiest  parts  of  the  work  to  produce — proximal 
contours  in  inlays — and  in  addition  it  has  been  my  practice  to  melt  a  pin-head  sized  piece  of  22-in. 
gold  upon  the  contact  point  of  the  inlay,  thus  giving  it  a  nicely  curved  surface  of  hard  gold.  That 
which  was  so  hard  to  secure,  and  at  the  same  time  so  important  to  secure,  in  a  malleted  filling,  is  now 
most  easily  produced  in  the  inlay. 

He  correctly  says  that  the  rubber  dam  has  been  eliminated  and  with  it  the  ligatures  and  the  hours 
of  painful  malleting.  I  would  also  add  that  half  of  the  pain  of  cavity  preparation  has  also  been  elim- 
inated, for  as  a  rule  the  preparation  of  a  cavity  for  an  inlay  does  not  require  so  much  cutting  in  the 
dentine  as  for  a  malleted  filling.  A  large  part  of  the  work  can  be  done  with  the  chisel  and  in  the 
enamel.  With  the  malleted  filling  the  time  was  when  the  operations  were  feats  of  endurance  on  the 
part  of  the  patient  and  dentist  rather  than  of  skill.  But  what  a  wonderful  change  has  come  about, 
not  only  in  the  humane  methods  of  technique  but  in  the  final  result.  For  who  can  deny  that  a  cemented 
filling  is  not  a  better  saver  of  teeth,  a  support  rather  than  a  strain  upon  frail  walls,  a  preservative  of 
color  and  one  of  less  thermal  conducting  property? 

The  essayist  is  too  modest  in  what  he  says  regarding  gold  crowns.  In  my  own  practice  the  inlay 
has  taken  the  place  of  fully  50  per  cent,  of  the  gold  crowns  formerly  used.  Sufficient  time  has  now 
elapsed  to  test  the  merits  of  the  inlay,  and  viewed  as  a  method  of  practice,  I  regard  it  as  the  most 
revolutionizing  step,  all  things  considered,  taken  in  dentistry  in  the  past  decade. 

Dr.  Henry  Barnes,  Cleveland:  From  the  secretary  I  received  a  communication  stating  that  I 
have  had  a  large  experience  in  cast  gold  inlay  work,  and  requesting  that  I  should  discuss  the  paper. 
As  a  matter  of  fact,  my  experience  has  profited  me  nothing,  for  I  have  not  succeeded  to  my  satisfaction 
in  this  field. 

There  are  those  who  claim  success  and  I  have  seen  beautiful  work  by  this  method.  Not  suc- 
ceeding myself  I  reasoned  that  the  thing  for  me  to  do  was  the  thing  that  I  could  best  do,  so  if  agreeable 
to  you  I  will  briefly  outline  the  method  which  I  am  using. 

Before  outlining  the  method,  I  desire  to  state  that  the  cast  method  is  in  no  wise  condemned  except 
so  far  as  I  am  personally  interested.  Several  months  ago  Dr.  Alexander,  of  North  Carolina,  called 
upon  me  and  outlined  his  method  of  packing  moss  fiber  gold  into  a  cavity,  removing  same,  investing, 
and  then  melting  22k.  gold  plate  into  the  mass.  My  cavity  preparation  was  such  that  most  of  the 
gold  remained  in  the  cavity  when  attempting  to  remove  the  mass.     However,  thought  was  stimulated 


THE  CAST  GOLD  INLA  Y  153 

and  a  gold  matrix  was  placed  within  the  cavity  and  this  was  filled  with  moss  fiber  gold  (I  now  use 
Ney's  No.  4  soft  gold  foil  with  equal  success  and  a  saving  of  time),  the  whole  removed  from  the  cavity, 
placed  on  the  charcoal  block  and  22k.  gold  plate  sweated  into  the  mass,  using  the  Lane  blow-pipe  and 
the  mouth  as  a  bellows.  A  little  practice  with  this  method  will  surprise  you  in  the  rapidity  with 
which  the  work  can  be  performed.  Many  cases  can  be  made  in  the  time  required  to  make  the  wax 
model,  and  the  margins  are  assured  if  your  technique  has  been  correct.  To  shape  the  gold  matrix  of 
.3-1000  pure  gold,  orange  or  other  suitable  wood  is  used,  spatulate  at  one  end  and  rectangled  at  the 
other,  also  another  stick  is  used  shaped  at  one  end  exactly  as  your  grandmother  used  to  notch  her 
clothes  pole;  this  serves  to  smooth  matrix  over  the  margins.  Do  not  use  metallic  instruments  on 
matrix  except  the  matrix  forming  instruments  at  the  cervical  margins.  Use  no  Hux  in  sweating  gold 
into    fiber. 

Question:  How  do  you  get  occlusion?  Answer:  Fill  matri.x  to  occlusion  and  at  the  last  use  a 
little  flux  over  occlusal  surface,  including  matri.x  margin,  then  sweat  22k.  gold  plate  over  same.  No 
flux  is  used  previous  to  this  time. 

Question:  Do  you  condense  the  fiber  gold?  Answer:  Only  as  much  as  can  be  done  by  the  hand 
with  the  wood  point  and  to  the  anatomical  form.  If  you  fail  to  obtain  a  good  cast  inlay  grind  margins, 
place  matrix  in  cavity,  cast  in  this,  remove  and  sweat  22k.  to  cast  and  matrix. 

Dr.  H.  C.  Kenvon,  Cleveland:  From  the  tenor  of  Dr.  Myer's  paper  we  naturally  conclude  he 
is  an  inlay  enthusiast.     And  while  I  agree  with  much  he  has  said,  I  cannot  subscribe  to  all  of  it. 

The  first  thing  I  want  to  take  exception  to  is  this: 

"In  a  crude  way  this  method  was  adopted  in  my  practice  and  from  that  day  to  this  I  cannot  recall 
a  single  instance  where  I  have  used  gold  in  filling  teeth  by  any  of  the  older  methods,  and  were  I  com- 
pelled to  again  resort  to  the  practice  of  placing  gold  in  cavities  as  we  have  been  compelled  to  do  in 
years  past,  filling  teeth  would  be  the  last  business  that  would  appeal  to  me.  " 

Unless  his  practice  differs  much  from  mine,  I  could  not  subscribe  to  such  a  statement  as  that. 
I  do  not  believe  that  all  the  cases  requiring  fillings  can  be  filled  with  inlays  more  easily  than  with  some 
other  kind  of  filling,  especially  the  malleted  gold  filling.  I  believe  there  are  some  valuable  things  to 
be  gained  from  the  malleted  gold  filling,  put  in  under  intelligent  present-day  methods.  I  do  not  think 
that  a  statement  like  this  should  go  unchallenged  when  we  have  young  students  in  our  audience  who 
are  apt  to  take  statements  of  essayists  as  authority  rather  than  opinion. 

I  want  to  endorse  fully  what  he  says  in  regard  to  the  use  of  the  inlay  in  the  place  of  the  crown . 
I  do  not  believe  the  inlay  comes  to  replace  the  malleted  gold  filling  so  much  as  it  does  some  other 
operations.  I  scarcely  use  the  gold  crown  at  all  now  except  in  cases  of  bridge  work,  where  I  think  an 
inlay  may  not  be  of  sufficient  strength  to  carry  its  portion  of  the  stress.  In  such  cases  I  still  use  the 
gold  crown  because  I  can  get  stronger  support.  The  essayist  has  called  attention  to  some  very  impor- 
tant points  which  ought  to  change  the  minds  of  those  who  are  opposed  to  the  gold  inlay,  and  the  cast 
inlay  in  particular.  One  is  the  question  of  separation  of  teeth  and  the  elimination  of  the  rubber  dam. 
I  cannot  conceive  of  a  sensible  operator  putting  a  large  gold  filling  in  a  tooth  that  is  subject  to  pyorrhea, 
and  I  cannot  conceive  of  a  humane  man  putting  a  malleted  filling  in  the  mouth  of  a  very  sensitive, 
nervous  woman  whose  health  is  so  poor  that  she  cannot  sit  through  such  an  operation  without  a  case 
of  nervous  exhaustion.  And  I  think  the  doctor  is  timely  in  calling  attention  to  the  fact  that  we  are 
practicing  humane  dentistry  as  far  as  we  know  how.  I  think  we  ought  to  emphasize  these  methods, 
and  that  is  one  of  the  strong  arguments  in  favor  of  the  inlay  method  of  filling  teeth.  There  is  much 
that  might  be  said  as  to  whether  we  should  use  the  gold  inlay  or  the  malleted  filling.  A  man  might 
better  make  a  gold  inlay  than  a  poor  filling.  If  he  is  going  to  leave  the  cracks  there  at  all  it  is  better 
to  have  the  cement  in  them  than  not. 

Dr.  J.  V.  CoNZETT,  Dubuque,  la.:  I  am  diametrically  opposed  to  some  of  the  things  that  have 
been  said,  and  I  very  much  deplore  the  fact  that  any  man  will  get  up  before  a  society  of  scientific  men 
and  say  that  he  would  not  use  a  malleted  filling  in  any  place,  because  the  inlay  is  a  new  process  and  the 
gold  filling  is  as  old  as  dentistry  itself.  We  know  what  the  gold  filling  will  do,  we  have  great  hopes  of 
what  the  inlay  will  accomplish,  but  I  believe  the  man  is  very  short-sighted  who  will  cast  aside  the 
gold  filling.  Things  have  come  and  things  have  gone  which  were  going  to  take  the  place  of  the  gold 
filling,  and  from  time  to  time  men  have  advised  us  to  throw  away  our  pluggers;  but  the  men  who  have 
done  so  have  afterward  been  found  sneaking  around  in  the  ash  pile  hunting  for  them.  I  want  to  con- 
demn just  as  severely  as  it  is  possible  to  condemn,  any  man  who  will  advocate  the  placing  of  inlays 
to  the  e.xclusion  of  gold   fillings. 

We  deplore  excessive  extension  for  prevention.  I  advocate  extension  for  prevention,  but  it  should 
not  be  abused.  You  and  I  have  no  business  to  cut  away  tissue  that  can  be  saved.  It  may  be  that 
there  are  some  men  who  ought  to  use  cast  gold  inlays  in  every  place,  because  they  haven't  the  ability 


154  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

to  acquire  the  technique  to  make  gold  fillings.  I  do  not  believe  Dr.  Myers  is  that  kind  of  a  man  be- 
cause I  know  of  the  success  he  has  had  with  gold  foil. 

I  want  you  to  understand  that  I  am  not  condemning  the  gold  inlay.  I  said  in  my  paper  that 
it  had  come  to  stay  and  I  believe  that  it  is  going  to  have  increasingly  larger  uses  in  restoring  lost  tooth 
tissue.  But  I  do  believe  that  the  man  who  is  going  to  be  a  good  operative  dentist  should  be  able  to 
use  any  material.  It  is  a  question  of  judgment;  it  is  a  question  of  technique;  study  the  conditions 
and  then  employ  the  method  which  will  best  meet  the  conditions  and  restore  the  tissue  to  the  best 
usefulness. 

The  doctor  speaks  of  extracting  a  larger  fee  from  our  patients.  I  am  glad  I  do  not  have  to  go  out 
and  rope  them  in.  They  come  in.  I  do  not  believe  that  the  men  who  are  practicing  dentistry  as  it 
should  be  practiced  in  these  modern  days  have  to  go  out  after  patients.  I  do  not  believe  that  the 
patients  come  to  us  with  fear  and  trembling.  Just  last  week  I  had  a  lady  come  to  me  who  had  some 
most  abominable  fillings  in  her  teeth.  If  you  had  seen  them  you  would  have  thought  that  the  dentist 
had  used  no  cavity  preparation  whatever.  ,She  came  to  me  in  fear  because  of  the  experience  she  had 
had.  That  lady  was  at  lunch  with  my  wife  and  she  said  it  was  a  positive  pleasure  to  have  her  teeth 
filled  in  my  office.  I  simply  mean  by  that  that  because  of  our  modern  cavity  preparation  and  the 
modern  methods  of  using  instruments,  it  is  not  necessary  to  infiict  the  pain  that  was  necessary  years 
ago.  I  should  hate  to  be  a  dentist  who  would  have  to  consume  three  or  four  hours  in  making  a  malleted 
filling.  I  believe  I  would  quit  dentistry.  I  do  believe  when  statements  of  this  kind  are  made  before 
scientific  bodies  that  we  should  get  the  other  side.  I  believe  that  if  we  were  to  wipe  out  the  necessity 
for  making  the  gold  filling— that  if  the  other  methods  were  to  take  the  place  of  the  gold  filling — it 
would  yet  be  best  for  us  to  practice  the  methods  of  the  technique  of  the  gold  filling  in  our  schools  for  the 
perfecting  of  our  pupils,  because  there  is  nothing  that  will  so  stimulate  a  student  as  the  making  and 
perfecting  of  one's  self  in  the  filling  of  teeth  with  gold  foil. 


A  COMBINATION  CAST  CROWN 

By  O.  H.  Simpson,   D.D.S.,  Dodge  City,   Kansas. 

The  all-cast  crown  has  about  as  many  objectionable  features  as  either  the  seam- 
less or  cap  and  band  crown,  and  it  occurs  to  me  that  by  combining  the  two  processes 
a  much  superior  crown  can  be  made. 

In  the  all-cast  crown  it  is  practically  impossible  to  get  band  bclcnv  margin  of 
gum  without  an  element  of  guess  work;  besides  the  band  is  apt  to  be  clumsy  and  has 
little  or  no  tensile  strength,  which  renders  it  unfit  for  support  of  bridge  work.  If 
it  were  not  for  the  fact  that  the  seamless  is  less  angular  in  form  than  the  average 
cap  and  band  crown,  and  the  absence  of  the  solder  line,  there  would  never  be  a  seam- 
less crown  used. 

The  ease  with  which  the  band  can  be  adapted  to  the  root  makes  up  in  a  great 
measure  for  the  difficulty  experienced  in  getting  a  graceful  union  between  cap  and 
band.  If  any  extensive  reinforcing  is  done  there  is  always  more  or  less  risk  connected 
with  the  process,  and  besides,  it  is  difficult  to  get  the  thickness  where  it  is  most 
desired,  and  the  solder  is  apt  to  shift  at  any  subsequent  heating  of  the  crown. 


Fig.] 


Fig.  2 


Fig.  3 


Most  of  the  objectionable  features  can  be  overcome  by  cutting  the  band  wide 
enough  to  articulate  edge  of  band  with  the  opposing  teeth.  Place  band  on  root, 
festoon  and  adapt  band  to  circumference  of  root.  The  band  is  readily  articulated 
with  opposing  teeth  by  having  patient  open  and  close  the  mouth  a  few  times,  thus 
showing  where  to  trim  away  the  band.  Be  sure  to  leave  band  on  the  buccal  surface 
as  long  as  the  cusps  of  the  adjoining  teeth,  as  the  distinct  feature  of  this  way  of  making 
a  crown  is,  that  the  band  and  cusps  are  made  continuous,  doing  away  with  the  solder 
joint  between  cusps  and  band.  The  cusps  can  be  made  any  length  or  form  b\'  cutting 
notches  in  band  and  contouring  with  pliers,  as  is  show'n  in  Fig.  1. 

The  band  being  longer  it  furnishes  the  operator  a  better  opportunity  to  contour 
than  the  old  style  of  narrow  band.  Place  band  back  on  root  and  readapt  to  proximal 
teeth.  If  it  is  a  short  stump,  partly  fill  the  open  end  of  band  with  investment, 
leaving  room  for  sufficient  thickness  of  wax  to  make  cusps  of  desired  thickness. 


150 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


Finish  filling  the  band  with  wax  and  have  the  patient  bite  down  to  get  the  articula- 
tion. Carefully  remove  band,  carve  wax  to  correct  tooth  form,  preserving  in  a 
measure  the  articulating  surfaces  made  by  wax  on  opposing  teeth.  Fill  upper  end 
of  band  after  removing  from  the  root  with  investment;  insert  sprue  and  proceed  as 
with  any  other  casting.     See  Fig.  2. 

I  believe  that  the  advantage  of  this  way  of  constructing  a  crown  over  the  short 
band  and  cast  cusps  can  readily  be  seen,  as  the  gold  used  in  casting  is  not  always 
the  same  color  as  the  band,  and  if  there  is  any  slight  defect  in  the  casting  process  it  is 
less  conspicuous,  as  it  is  underneath,  instead  of  on  the  side. 

I  have  found  Fig.  3  particularly  adapted  to  the  support  of  bridge  work  on 
lower  cuspids  where  the  patient  objects  to  devitalization  and  Richmond  crowns. 
Prepare  tooth  as  is  shown  in  Fig.  4,  cutting  key  seats  and  making  sides  as  nearly 
perpendicular  as  the  case  will  permit.     Make  band  open  front  and  back,  making  it 


Fig.  4 


Fig.  5 


Fig.  6 


fit  snug  at  anterior  cervical  and  sides.  Allow  band  to  gap  open  slightly  on  the 
lingual  surface  so  that  the  keys  and  back  will  cast  in  one  piece.  Figure  5  shows 
where  I  have  sealed  or  melted  wax  keys  and  wax  back  on  dry  band  before  forcing 
it  down  over  prepared  tooth.  Wax  will  not  adhere  so  readily  to  a  moist  band,  hence 
the  precaution  to  attach  the  keys  and  back  before  forcing  it  over  prepared  tooth. 
Carefully  remove;  insert  sprue  wherever  it  is  indicated. 

This  band  will  greatly  strengthen  this  form  of  bridge  support,  and  is  seldom 
noticeable  in  conversation.  With  care  the  gold  at  the  side  and  cutting  edge  can  be 
almost  entirely  concealed,  as  is  illustrated  in  Fig.  3.  Sometimes  when  the  band  is 
not  sufificiently  heated,  or  is  too  badly  oxidized,  the  cast  portion  fails  to  adhere  to 
band.  For  this  reason,  I  advocate  soldering  the  two  together.  The  seam  being  so 
perfect  only  a  small  quantity  of  solder  is  required. 

Figure  6  illustrates  side  view  of  band  Figure  3  before  wax  back  and  keys  are 
attached. 


DESCRIPTION  OF  AN  INTERESTING  CASE  RESTORED  BY  ALL-PORCE- 
LAIN BRIDGE  AND  BRIDGES  UPON  CAST  BASES 

By  J.   M.  Thompson,  D.D.S.,   Detroit,   Mich. 

During  the  last  week  of  July,  1908,  Miss  A.,  a  non-resident  patient,  presented 
for  restoration  one  of  the  worst  cases  of  broken  down  roots  (which  had  previously 
supported  their  own  and  artificial  crowns)  that  it  has  ever  been  my  fortune  to  see. 
The  necessities  of  the  case  and  the  fact  that  it  would  be  of  interest  to  others  did  not 
impress  me  sufficiently  at  first  to  warrant  my  making  photos,  models,  etc.,  before 
beginning  the  work.  It  was  after  having  an  X-Ray  picture  taken  to  locate  a  missing 
cuspid  that  it  impressed  me  as  a  remarkable  case. 

Figure  1,  as  presented  here,  is  the  X-Ray  picture,  and  that  it  may  be  fully 
understood,  the  reader  will  simply  assume  that  he  is  looking  from  within  outward, 
and  the  description  will  be  easily  followed. 

Reading  from  left  to  right,  we  find  the  first  bicuspid  the  only  natural  crown  in 
the  upper  jaw.     Letter  "a"  shows  a  broken  down  lateral  root  supporting  a  crown 


Fig.  1 


Fig. 


held  in  jKJsition  In-  a  twist  of  cotton.  Letter  "b"  shows  uncrupted  cuspid  resting 
against  apex  of  broken  down  central  root.  Letter  "c"  shows  porcelain  crown  with 
dowel  extending  into  central  root,  around  which  is  a  roll  of  cotton  which  retained  it  in 
the  gum  and  tooth.  Letter  "d" shows  right  central,  a  devitalized  tooth  with  an  inlay 
set  in  one  side  of  the  root  for  the  purpose  of  properly  shaping  the  end  so  that  a  porce- 
lain jacket  crown  could  be  fitted,  the  crown  being  shown  in  position.  Letter  "e" 
shows  another  porcelain  crown  also  held  in  position  by  a  twist  of  cotton,  and  letter 
"f  "  another  held  in  by  the  same  method.  It  is  needless  to  say  that  the  patient  was 
somewhat  of  an  expert  in  the  wrapping  of  cotton  around  the  dowels  of  these  crowns, 
and  two  of  them  were  so  securely  fastened  that  considerable  force  was  necessary 
for  their  removal. 


158 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


Figure  2  shows  central  incisor  with  cotton  still  in  place,  having  been  worn  part 
of  a  day  before  the  root  was  removed. 

A  bridge  of  three  teeth  was  first  made  for  the  lower  jaw  (right  side),  consisting 
of  a  shell  crown  upon  the  third  molar,  a  Davis  crown  upon  a  cast  base,  for  the  first 
molar,  with  a  diatoric  molar  supported  between  them. 


Fig.  3 

The  root  of  the  first  molar  was  of  peculiar  type  (see  a,  b,  c  and  d,  Fig.  3),  having 
three  distinct  roots  with  a  perforation  separating  all  three.  The  surface  of  the  root 
was  ground  to  a  plain  surface  and  a  Davis  molar  ground  to  fit  the  tooth  as  perfectly 
as  possible,  and  in  shaping  the  porcelain  molar  it  was  necessary  to  place  it  in  the 
furnace  to  restore  the  glaze.  A  piece  of  No.  40  pure  gold  foil  was  then  burnished 
over  the  base  of  the  crown  and  a  post  forced  through  the  foil  into  the  hole  in  the 
crown.  The  soft  wax  was  then  placed  in  position  and  the  crown  pressed  down 
upon  the  root,  the  wax  protruding  through  the  perforation  somewhat.  This  was 
trimmed  off  and  again  adjusted,  and  then  removed  and  the  porcelain  crown  taken 
away  and  a  casting  was  made  with  gold  foil  in  place.  When  completed,  a  very 
thin  line  of  gold  was  all  that  would  give  any  evidence  of  its  being  used  upon  a 
gold  base. 


Fig.  4 


Fig.  5 


A  bridge  for  the  upper  jaw  (right  side)  was  then  made,  consisting  of  a  Davis 
crown  cuspid  upon  a  cast  base,  a  gold  shell  for  the  first  molar  with  two  bicuspids 
made  by  waxing  the  facings  into  place  and  forming  dummies  for  casting  and  then 
removing  the  facings  and  using  lead  pencil  points  to  preserve  the  holes  for  the  pins. 
Thus  we  have  a  bridge  without  putting  the  facings  through  the  fire. 


DESCRIPTION  OF  AN  INTERESTING  CASE  159 

Next  the  lateral,  "e,"  Fig.  1,  was  removed  and  a  crown  of  suitable  size,  shape, 
and  color  was  placed  in  position.  The  porcelain  jacket  was  then  removed  from  "d" 
Fig.  1,  and  the  root  prepared  with  a  facer  and  a  dowel  of  iridio-platinum  set  in 
position  to  support  one  end  of  the  bridge  which  was  to  be  made.  The  lateral  root, 
"a,"  Fig.  1,  which  may  be  noticed  as  in  the  place  of  the  missing  cuspid,  was  then 
prepared  to  support  the  other  end  of  the  bridge. 

An  impression  was  then  taken  and  duplicate  pins  placed  in  the  impression  so 
that  the  work  could  be  made  upon  the  model  and  so  constructed  that  it  would  draw 
with  perfect  ease.  Four  facings  were  then  selected  and  waxed  into  position  with 
pink  inlay  wax  upon  a  base  of  one-thousandth  inch  platinum,  which  had  been  pre- 
viously burnished  over  the  model.  New  porcelain  was  then  placed  upon  the  labial 
surfaces  of  the  facings  at  the  cervical  portion,  also  covering  the  platinum  to  quite  an 
extent.  This  was  then  placed  before  the  door  of  the  furnace  and  the  wax  melted 
out,  the  porcelain  holding  the  facings  in  their  relative  positions.  No  attempt  was 
made  at  forming  a  foundation  at  this  time,  as  it  was  necessary  to  form  a  block  of 
four  teeth  before  attaching  it  to  either  of  the  roots. 

When  they  were  removed  from  the  furnace  after  the  first  baking  they  were 
again  adjusted  to  the  model  and  pink  gum  body  laid  over  the  first  baking  and  the 
case  again  fired.  Having  secured  the  block,  it  was  adjusted  perfectly  to  the  model, 
and  having  made  a  platinum  foundation  upon  each  root  in  the  mouth,  the  block  was 
then  adjusted  directly  against  the  roots  which  were  to  support  it.  On  account -of 
possible  change  of  shape,  only  one  end  was  securely  fastened  at  a  time,  and  in  ^s' 
way  a  perfect  fit  was  secured,  and  Figures  4and  5  show  the  case  before  and  after  the 
work  had  been  finished. 


RESTORATION  OF  BROKEN-DOWN  ROOTS  OF  BICUSPIDS  AND  MOLARS 

BY  CAST  METHOD 

By  A.  W.  McCullough,  D.D.S.,  Pittsburg,  Pa. 

This  method  applies  principally  to  bicuspids  and  molars,  which  are  badly  de- 
cayed or  broken  down,  or  where  by  accident,  one  cusp  has  been  broken  off,  the 
break  extending  under  the  gum  line,  and  a  portion  of  tooth  remaining. 

First,  after  canals  are  placed  in  proper  condition,  pack  space  tightly 
with  some  good  temporary  stopping,  and  allow  to  remain  a  day  or  two. 
On  removing,  the  margins  will  be  exposed,  and  root  can  be  shaped  without  injury  to 
surrounding  tissues.  The  root  should  be  shaped  in  most  retentive  form,  leaving  a 
portion  of  remaining  cusp  for  strength  where  possible. 


k    i 


» 


Figs.  1,  2,  .3,  4  and  .j 

A  post  may  be  used  in  canal,  but  usually  its  being  so  short,  an  impression  of 
gold,  making  the  whole  in  one,  is  advisable.  After  root  is  shaped,  an  impression 
of  root  with  inlay  wax,  extending  into  canals,  properly  trimmed  to  margins,  is  now 
taken,  invested  and  cast. 

This  assures  perfect  adaption  to  root. 

Sprue  is  now  cut  off  and  cast,  the  part  fitted  into  root,  impression  taken  in 
plaster  or  compound,  model  made  and  selected  tooth  built  into  place  with  inlay 
wax;  allowing  it  to  extend  over  lingual  cusp  in  sort  of  a  hood  shape  to  give  strength 
and  retention,  and  then  carving  occlusion  to  articulation. 

Tooth  waxed  in  position,  model  is  then  trimmed  as  small  as  possible,  and  in- 
vested again,  put  on  fire  and  allowed  to  heat  slowly,  but  to  a  high  degree,  so  as  to 
assure  uniting  to  cast  base  and  less  liability  of  fracture  to  porcelain,  and  then  cast. 

If  model  has  been  well  shaped  and  smoothed,  it  will  require  but  little  polishing 
and  make  a  very  strong,  esthetic  crown. 


SUBGINGIVAL  AND  ROOT  CANAL  RESTORATION  IN  CROWN  WORK 

By  Edward  C.   Mills,  D.D.S.,  Columbus,  Ohio. 

This  method  is  offered  to  meet  the  requirements  in  those  cases  where  the  root 
has  become  extensively  destroyed  by  caries  and  disintegration,  and  the  root  canal 
enlarged  considerably  beyond  the  requirement  for  inserting  a  dowel.  To  obtain  free 
exposure  of  the  end  of  the  root,  tightly  press  away  the  soft  tissue  with  gutta  percha, 
repeating  the  procedure  at  subsequent  sittings,  if  necessary,  as  time  expended  at  this 
step  will  greatly  facilitate  accurate  adaptation  (Fig.  1).  After  removing  debris 
and  decay,  the  sharp  irregular  edges  should  be  carefully  ground  down  with  stones 
and  a  carborundum  root  facer.  If  sufficient  portion  of  the  edges  remains,  and  it  is 
desirable  to  use  a  banded  dowel  crown,  proceed  as  follows: 


Tube 


Inlay 


Tub. 


Inlay 


Tu.ll4j- 


j-yy, 


'^^/z 


/'^/// 


Irtla^ 


Zrrjg:JEZ 


I^estore  the  root  by  use  of  inlay  wax  or  modeling  compound,  carefully  trimming 
and  readjusting  until  the  periphery  of  the  root  is  re-established.  Excess  of  moisture 
is  then  removed  and  this  core  secured  in  position  by  powdered  gum  tragacanth. 

Measurement  for  the  band  is  now  made  by  using  Barbour's  No.  3  Irish  flax,* 
the  ends  twisted  until  the  thread  is  tightly  adapted  to  the  periphery  of  the  root; 
then  with  a  sharp  pointed  surgeon's  shears  the  thread  is  cut  closely  as  possible  to 
the  root.  The  advantage  of  the  thread  over  a  wire  is  the  pliability  of  the  former  as 
compared  with  the  springiness  of  the  latter.     After  cutting,  the  ends  can  be  brought 


162  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

together  and,  if  found  to  overlap,  can  be  trimmed  to  a  butt  and  an  accurate  measure- 
ment is  secured.  From  this  make  the  band  of  sufficient  width  so  as  to  permit 
trimming,  that  a  portion  may  extend  to  or  sHghtly  beyond  the  edge  of  the  portion 
restored  by  the  core. 

After  selecting  a  round  or  square  dowel  of  surplus  length,  take  inlay  platinum, 
1-1000  thickness,  and  wrap  closely  around  the  pin  at  least  twice,  making  a  sleeve, 
which  is  carefully  slipped  ofT  and  the  exposed  edge  secured  with  a  minute  particle 
of  solder.  The  sleeve  is  now  readjusted  to  the  dowel,  correct  gauge  obtained  and, 
with  a  bur  of  the  exact  size,  the  canal  is  extended  to  sufficient  depth.  The  band  is 
now  placed  in  position,  the  dowel  in  its  platinum  sleeve  is  coated  with  sufficient  inlay 
wax  and  pressed  firmly  to  place,  the  wax  is  trimmed  fhjsh  with  the  band  and  all 
carefully  removed.  The  band  is  readily  slipped  off  the  wax  and  the  dowel  from  its 
sleeve,  leaving  the  latter  extruding  through  the  wax  model,  as  shown  in  Fig.  2. 

Place  a  piece  of  graphite  coated  with  thin  plaster  in  the  sleeve,  invest  and  cast 
(Fig.  3).  After  polishing,  the  excess  length  of  sleeve  is  removed  and  the  inlay  thus 
formed  placed  temporarily  in  position.  With  the  band  previously  made,  the  cap  is 
completed  in  the  usual  manner,  adapted  to  place  on  the  root,  perforated  for  the  dowel 
at  the  proper  point,  and  the  latter  is  pushed  to  its  place. 

To  sustain  the  accurate  relation  of  the  dowel  to  the  cap,  a  piece  of  modeling 
compound  is  warmed  and  pressed  against  the  projecting  end  of  the  dowel  and  surface 
of  the  cap,  cooled  with  a  spray  of  water  and  carefully  detached.  If  the  cap  and  dowel 
fail  to  remove,  they  are  easily  placed  in  their  respective  positions  and  secured  by  a 
speck  of  wax.  They  are  now  invested,  being  careful  that  the  interior  of  the  cap  is 
filled  with  investment,  and  soldered  (Fig.  4). 

The  cap  with  the  dowel  is  now  polished,  and  with  the  tubed  inlay  in  position 
in  the  root,  it  will  be  found  to  pass  snugly  to  place.  The  tubed  inlay  is  then  cemented 
permanently  in  position  and,  with  the  cap  and  dowel,  the  crown  is  completed  in  the 
manner  desired. 

In  cases  where  a  band  is  not  desired  or  unavailable,  due  to  the  condition  of  the 
root,  the  inlay  with  the  sleeve  for  the  dowel  is  prepared  at  once  and  cemented  to 
place. 

This  method  of  restoration  reduces  the  amount  of  cement  to  a  minimum  and 
insures  an  accurate  and  determined  position  for  the  dowel. 


*Irish  flax  is  more  economical  and  superior  to  dental  floss  in  general  use  about  the  mouth, 
can  be  obtained  at  any  leather  supply  house. 


PORCELAIN  AND  GOLD  INLAYS 

By  A.  W.   Starbuck,   D.D.S.,  Denver,   Colo. 
Superintendent  of  Infirmary,  Colorado  College  of  Dental  Surgery,  Denver,  Colorado. 

In  presenting  these  articles  upon  porcelain  and  cfold  inlays,  it  is  the  desire  of  the 
writer  to  furnish  an  outline  of  procedure  which  has  proven  very  satisfactory  in  his 
hands,  as  well  as  his  many  students'.  He  claims  no  originality  to  any  of  the  methods, 
rather  it  is  a  collection  of  the  good  ideas  introduced  and  practiced  by  the  eminent 
porcelain  and  gold  workers  of  the  day. 

The  equipment  recommended  for  porcelain  inlays  may  be  criticised  by  many 
owing  to  its  simplicity.  But  as  this  is  intended  more  for  the  practitioner  who  has 
been  shut  out  from  the  use  of  porcelain  owing  to  the  extensive  and  e.xpensive  equip- 
ment supposed  to  be  necessary,  we  will  eliminate  special  instruments  as  much  as 
possible,  thus  showing  the  possibilities  using  the  ordinary  equipment  of  general 
practice. 


Fig.  1 


Fig.  2 


Fig.  3 


CAVITY  PREPAR.A.TION  FOR  PORCELAIN  INLAYS 

Generally  speaking,  cavities  for  porcelain  inlays  should  be  free  from  undercuts 
in  the  direction  in  which  the  matrix  is  to  be  removed.  There  should  be  Hat  seats  at 
right  angles  to  all  possible  stress  from  mastication.  All  walls  should  be  as  nearly 
as  possible  at  right  angles  to  the  surface  of  the  tooth.  And  all  margins  should  be 
sharp  and  not  beveled. 

The  cavities  here  presented  are  a  composite  of  the  good  points  gleaned  from  a 
careful  study  of  a  series  of  models  sent  the  writer  by  about  thirty  of  the  prominent 
porcelain  men  from  different  parts  of  the  country. 


164  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

GINGIVAL   CAVITIES 

Gingival  cavities  should  be  extended  only  to  include  all  the  decayed  area.  In 
doing  this,  endeavor  to  get  an  oval  or  kidney-shaped  cavity  as  it  is  extremely  difficult 
to  properly  insert  an  inlay  of  circular  outline.  This  extension  is  best  accomplished 
by  the  use  of  chisels  and  inverted  cone  burs.  In  this  class  of  cavities  there  are 
frequently  several  small  pits  on  initial  seats  ( if  decay.  These  are  best  united  by  the 
use  of  small  inverted  cone  burs.  Then  wi..h  chisels  break  down  the  overhanging 
enamel  walls.  This  operation  should  be  repeated,  first  using  the  inverted  cone  burs 
(increasing  the  size  each  time),  then  the  chisels  until  the  cavity  is  extended  to  sound 
margins  and  symmetrical  outline.  After  the  desired  outline  is  reached,  any  under- 
cuts that  may  be  present  should  be  cut  away  and  the  walls  made  parallel  by  the  use 
of  square-end  fissure  burs,  or  better  still,  a  similar-shaped  plug  finishing  bur. 

It  is  in  these  cavities  we  experience  so  much  difficult}'  in  securing  a  proper  color, 
especially  after  the  inlay  has  been  cemented  to  place.  Consequently  great  care 
should    be  exercised  in  getting  the  proper  alignment  of  the   margins,  also  proper 


Fig.  4  Fig.  5 

depth  to  the  cavity.  This  being  an  extremely  sensitive  portion  of  the  tooth  many 
inlays  are  failures  owing  to  o.  lack  in  depth  sufficient  to  give  enough  bulk  to  the 
porcelain  to  exclude  the  influence  of  the  cement,  saying  nothing  of  the  strength  of 
the  inlay. 

Many  will  criticise  the  use  of  the  parallel  walls,  citing  the  difficulty  of  burnishing 
a  matrix  to  a  cavity  of  this  nature.  This  objection  you  will  find  entirely  done  away 
with  in  the  methods  suggested  later  for  forming  the  matrix  for  this  class  of  cavities. 
The  main  objections  to  flaring  walls  are  the  lack  of  retention  and  the  objectionable 
change  of  color  in  the  inlay  from  cement.  The  nearer  you  can  get  this  cement  wall 
parallel  to  the  line  of  vision  the  less  it  will  change  the  color  of  the  inlay. 

A  final  inspection  of  the  cavity  should  be  made  to  make  sure  there  are  no 
irregularities  or  small  nicks  in  the  margins.  This  is  best  accomplished  with  the  use 
of  a  lens.  The  marginal  walls  should  be  smooth,  yet  not  polished,  as  cement  will 
not  adhere  properly  to  a  polished  surface. 


PORCELAIN  AND  GOLD  INLAYS  16r> 

The  writer  can  not  recommend  too  strongly  the  plan  of  seating  the  patient  in  a 
normal  position  at  this  time  and  carefully  viewing  the  walls  of  the  cavity  to  make 
sure  they  are  parallel  to  the  line  of  vision,  as  this  is  so  essential  to  the  appearance  of 
the  inlay  when  set.  How  often  have  we  viewed  an  inlay  with  pride  when  the  patient 
was  tilted  back  in  the  chair,  only  to  be  disappointed  even  to  the  removal  of  the  inlay 
when  the  patient  was  standing  or  sitting  in  a  normal  position. 

SIMPLE   PROXIMAL   CAVITIES 

Among  the  many  excellent  ideas  brought  forth  and  taught  by  Dr.  Black  and  his 
disciples  is  one  point  which,  if  possible,  is  of  greater  value  to  the  porcelain  worker 
than  to  the  gold  worker,  and  that  is: 

STUDY   THE   OCCLUSION 
as  the  durability  of  an  inlay  depends  largely  upon  the  manner  in  which  stress  is 
brought  to  bear  upon  it.     This  one   thing  should   receive  our  first  consideration. 


Fig.  6  Fig.  7 

In  cases  where  there  is  excessive  stress  porcelain  is  contra-indicated.  However,  in 
ca,ses  with  moderate  or  ordinary  stress  porcelain  will  prove  satisfactory,  provided 
proper  cavity  preparation  is  considered  and  the  inlay  is  carefully  baked. 

The  patient  should  be  requested  to  close  the  teeth,  first,  normally,  then  have  him 
move  his  jaws  in  such  a  manner  that  every  peculiarity  of  occlusion  at  that  particular 
point  can  be  carefully  noted.  Frequently  what  at  first  seemed  a  favorable  case  has 
proved  dangerous  when  considering  the  lateral  movements  of  the  jaws.  Many  such 
cases  may  be  improved  by  slight  grinding  of  an  angle  of  the  tooth  or  the  tip  of  a  cusp 
when  this  portion  is  slightly  elongated. 

In  inlays  where  stress  of  mastication  is  a  factor  of  consideration  they  should 
always  be  removed  in  the  direction  from  which  such  stress  comes.  There  should  also 
be  fiat  seats  antagonizing  any  force  brought  to  bear  from  this  direction. 

Generally  speaking,  proximal  cavities  should  be  so  prepared  that  there  will  be 
no  difficulty  in  removing  the  matrix  where  there  is  but  slight  separation. 

Fortunately,  the  lingual  wall  is  generally  the  weaker,  consequently  it  is  a  less 
sacrifice  to  cut  away  this  wall  to  permit  the  easy  removal  of  the  matrix  and  this  is 


166 


PRACTICAL   MANUAL   OF    DENTAL   CASTING 


the  logical  procedure  in  the  upper  incisors  and  cuspids  (the  teeth  we  are  dealing  with 
mostly),  unless  we  have  an  abnormal  occlusion. 

In  preparing  a  single  proximal  cavity  in  an  upper  incisor,  first  break  down  the 
weak  enamel  walls,  using  chisels  or  hatchet  and  hoe  excavators.  Then  with  smooth, 
square-end  fissure  burs  in  the  right  angle  entering  from  the  lingual  the  cavity  may 
be  formed. 

The  cavity  should  be  slightly  larger  at  the  lingual  than  it  is  at  the  labial  to 
permit  the  removal  of  the  matrix.  The  axial  wall  should  be  as  nearly  flat  as  possible 
and  parallel  with  the  long  axis  of  the  tooth.  The  incisal  and  gingival  walls  should  be 
at  right  angles  to  this.  These  walls  are  formed  with  the  sides  of  the  bur,  while  the 
square  end  forms  a  flat  seat  under  the  labial  plate.  Any  imperfections  following  the 
use  of  the  bur  may  be  remedied  by  the  use  of  the  hatchet  and  hoe  excavators.  All 
margins  should  be  made  at  right  angles  to  the  surface  and  should  be  sharp  and  well 
defined.  At  this  time  the  patient  should  be  placed  in  a  normal  position  and  a  close 
inspection  made  of  the  labial  margin  to  make  sure  it  is  parallel  to  the  line  of  vision, 
and  if  not  it  should  be  so  altered  as  to  remedy  the  trouble. 


Fig.  S 


Fig.  9 


Fig.  10 


It  is  needless  to  say  that  all  remaining  decay  should  be  removed.  In  case  this 
.should  cause  undercuts  or  pockets  they  may  be  filled  with  cement. 

The  important  points  for  consideration  are:  First,  the  caviiy  should  be  larger 
at  the  lingual  than  at  the  labial;  second,  the  axial  wall  should  be  flat;  third,  the  incisal 
and  gingival  walls  should  be  at  right  angles  to  the  axial  wall;  fourth,  there  should  be  a 
flat  seat  under  the  labial  plate;  fifth,  all  margins  should  be  at  right  angles  to  the  sur- 
face and  not  beveled;  sixth,  the  labial  wall  should  be  so  modified,  if  necessary,  to  make 
it  parallel  to  the  line  of  vision. 

In  cases  where  the  lingual  wall  is  strong  and  the  cavity  is  near  the  labial  surface 
the  preparation  may  be  so  modified  to  permit  the  matrix  being  removed  to  the  labial. 
This  would  be  permissible  only  in  very  small  cavities  and  those  caused  by  an  over- 
lapping tooth  and  then  when  it  did  not  involve  the  lingual  wall. 


PORCELAIN  AND  GOLD  INLAYS 


167 


The  preparation  of  a  cavity  in  a  lower  incisor,  regarding  the  manner  of  removing 
the  matrix,  would  depend  largely  upon  the  condition  of  the  labial  and  lingual  walls, 
but  it  would  be  preferable  to  remove  to  the  labial. 

In  cavities  of  this  class  there  has  been  considerable  criticism  by  many  as  to 
whether  porcelain  was  indicated  in  any  case.  However,  time  has  proven  that  they 
will  stand,  under  proper  conditions,  even  eciual  to  the  average  gold  fillings. 

Again,  it  is  of  the  greatest  importance  to 

STUDY    THE    OCCLUSION 

This  is  something  that  should  become  a  habit  with  every  dentist.  Very  few 
men  even  think  of  the  occlusion  until  the  patient  goes  to  leave  the  chair  and  com- 


Ki;4.  II  Fig.  12  Fig.  13 

plains  of  the  filling  or  crown  being  too  high.  By  carefully  observing  the  occlusion 
on  the  start,  it  may  prevent  after  disaster  and  possibly  change  the  entire  procedure. 

In  cases  of  an  edge  to  edge  bite  and  showing  considerable  wear,  porcelain 
should  be  used  with  great  caution,  if  at  all.  While  teeth  with  normal  occlusion  may 
be  filled  with  porcelain  if  due  consideration  is  made  of  the  preparation  of  the  cavit>- 
and  the  results  will  be  permanent  and  serviceable.  In  ail  cases  we  should  endeavor 
to  get  the  maximum  thickness  of  porcelain  possible.  The  method  used  by  some  of 
leaving  the  labial  plate  and  building  up  the  lingual  plate  only,  at  the  incisal  edge  or 
vice-versa,  is  a  dangerous  and  frequently  disastrous  procedure. 

The  method  of  cutting  away  the  labial  plate,  (Figs.  8,  9,  10),  to  a  straight  line 
parallel  with  the  long  axis  of  the  tooth  and  depending  upon  the  depth  of  cavity  and 
parallel  gingival  and  incisal  walls  upon  the  lingual,  has  merit  in  cases  where  the  tooth 


Fig.  14 

is  of  considerable  thickness  labio-lingually  and  there  is  sufficient  dcptii  of  cavity  in 
the  direction  of  the  pulp,  but  as  a  rule  there  is  not  sufiicient  anchorage  to  withstand 
the  stress  of  mastication.     The  better  method,  and  I  think  the  one  adopted  by  the 


168 


PRACTICAL   MANUAL   OF    DENTAL   CASTING 


best  authorities,  is  to  gain  additional  retention  by  extending  the  cavity  on  the  incisal 
edge,  forming  a  step. 

In  shaping  the  labial  margins,  it  is  preferable  to  extend  so  all  portions  of  the 
margins  will  either  be  at  right  angles  or  parallel  to  the  long  axis  of  the  tooth.  For 
example,  if  we  had  a  tooth  broken  down  as  illustrated  in  Figure  11,  it  should  be  cut 
away  with  a  carborundum  stone  until  the  margin  assumes  lines  illustrated  in  Fig. 
12,  rather  than  shaping  it  as  illustrated  in  Fig.  1.3,  or  again  in  a  more  extreme  case  as 
shown  in  Fig.  14,  instead  of  simply  smoothing  the  surface  of  the  break,  leaving  the 
general  view  as  it  is,  it  is  preferable  to  form  a  series  of  steps  as  shown  in  Fig.  15. 
A  cavity  thus  prepared  will  show  less  and  in  many  cases  have  increased  retention. 
The  principal  reason  for  such  a  procedure,  however,  is  the  fact  that  the  fine  line  of 
union  takes  on  the  appearance  of  a  developmental  groove,  or  a  natural  crack  in  the 


Fig.  16 


Fig.  17 


Fig.  18 


tooth  and  is  hardly  noticeable.  An  inlay  that  is  a  shade  or  two  ofT  in  color  will 
hardly  be  noticeable,  while  a  bias  margin  is  noticeable  even  with  a  perfect  match. 

The  m.atrix  should  be  removed  in  the  direction  from  which  occlusal  stress  conies; 
namely,  to  the  lingual  in  the  upper  anterior  teeth  with  normal  occlusion.  In  all 
cases  there  should  be  flat  seats  antagonizing  any  such  stress. 

In  preparing  cavity  Figs.  8,  9,  10,  the  labial  plate  may  be  formed  with  a  knife- 
edge  carborundum  stone.  The  lingual  plate  is  removed  with  chisels  and  hoe  ex- 
cavators; then  with  a  smooth  fissure  bur  extend  and  shape  the  gingival  and  incisal 
walls  of  the  cavity  sufficiently  to  permit  the  easy  removal  of  the  matrix.  The  axial 
wall  should  be  flat  and  parallel  with  the  long  axis  of  the  tooth  and  the  gingival  and 
incisal  walls  at  right  angles  to  this.  The  junction  between  these  walls  should  be  a 
well  defined  angle  and  not  rounded  as  some  advocate.  With  the  end  of  the  bur  a 
fiat  seat  is  formed  under  the  labial  plate.  Then  remove  any  remaining  decay  and 
carefully  inspect  all  margins  to  make  sure  they  are  sharp  and  well  defined.  Finally, 
.seat  the  patient  in  a  natural  position  and  carefully  examine  the  labial  wall  to  make 
sure  it  is  parallel  to  the  line  of  vision  from  the  cavo-surface  angle  inward.     In  other 


PORCELAIN  AND  GOLD  INLAYS 


169 


words,  only  the  cavo-surface  angle  should  be  in  view.  Especial  attention  should  be 
given  to  the  gingivo-labial  angle,  as  it  is  at  this  point  we  have  a  tendency  to  cut 
insufficiently.  A  cavity  of  this  nature  is  seldom  indicated  as  it  lacks  sufficient 
incisal  retention  if  there  is  any  great  amount  of  stress. 

The  method  preferable  and  generally  used  is  one  where  additional  incisal  re- 
tention is  obtained  by  use  of  a  step. 

The  main  portion  of  the  labial  wall  and  the  step  are  formed  with  a  knife-edge 
carborundum  stone.  It  will  be  noticed  in  Fig.  16  that  the  gingival  wall  of  the  step 
is  not  quite  at  right  angles  to  the  long  axis  of  the  tooth,  but  dips  down  slightly  as 
it  approaches  the  axial  wall  of  the  step.  This  is  necessary  to  afford  retention  from 
dislodgment  to  the  approximal  as  the  fulcrum  is  at  the  cavo-surface  angle  of  the 
gingival-surface;  hence,  the  inlay  in  the  step  moves  incisally  slightly,  if  dislodged. 


Fig.  19 


Fig.  20 


Fig.  2] 


By  examining  Fig.  17,  it  will  be  noticed  that  the  line  of  the  pulpal  wall  of  the 
step  is  broken,  thus  affording  additional  strength  to  the  porcelain  at  this  point. 
This  is  formed  with  a  small  inverted  cone  bur  held  parallel  to  the  long  axis  of  the 
tooth.  The  diameter  of  the  step  mesio-distally  should  be  about  two  millimeters 
ordinarily  and  about  the  same  diameter  inci.so-gingivally  at  the  narrowest  point;  or, 
in  other  words,  should  be  of  sufficient  dimensions  to  give  strength  to  the  porcelain. 

The  main  portion  of  the  cavity  is  formed  with  a  smooth  fissure  bur  in  the  right 
angle.  Special  attention  should  be  given  to  the  gingival  wall  to  have  it  at  right 
angles  to  the  long  axis  of  the  tooth,  also  to  have  a  flat  seat  under  the  labial  wall. 
Many  advocate  grooving  this  seat  near  the  axial  wall,  but  this  is  a  very  dangerous 
procedure  as  there  is  danger  of  cutting  through  the  dentine  to  the  enamel,  which 
would  completely  destroy  the  strength  of  the  wall,  as  there  is  no  strength  to  enamel 
when  not  supported  by  dentine.  Nor  is  a  groove  along  the  gingival  necessar\'  if  that 
wall  is  perfectly  flat  and  at  right  angles  to  stress. 

Again  inspect  all  margins  carefully  to  make  sure  they  are  smooth  and  sharp 
and  note  the  angle  of  the  labial  wall,  especially  the  gingivo-labial  angle  in  the  main 
portion  of  the  cavity  and  the  gingival  wall  of  the  step. 


170  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

If  the  labial  wall  is  thin  and  lacks  sufficient  dentine  to  give  it  adequate  strength, 
there  should  be  an  additional  step  made  inciso-gingivally  upon  the  lingual  surface. 

This  is  formed  with  an  inverted  cone  bur  in  the  right  angle  and  should  extend 
from  the  incisal  step  to  the  gingival  seat.  The  step  should  be  on  an  average  about 
one  and  one-half  millimeters  wide  and  a  corresponding  depth.  Some  authorities 
advise  a  groove  extending  inciso-gingivally  along  this  step,  which  has  advantages  in 
many  cases,  but  care  should  be  taken  to  consider  carefully  the  location  and  size  of 
the  pulp  in  live  teeth. 

INCISAL    RESTORATIONS 

In  considering  cavities  involving  the  incisal  third  of  the  six  anterior  teeth,  it 
might  be  well  to  divide  them  into  two  classes:  First,  fractures;  second,  atrophied 
teeth. 

In  fractures,  the  teeth  may  be  broken  diagonally  or  almost  at  right  angles  to  the 
long  axis  of  the  tooth.  In  either  case,  the  labial  margins  should  be  cut  at  right 
angles  to  the  long  axis  of  the  tooth.  If  the  break  does  not  involve  both  angles,  as 
in  Fig.  22,  the  margin  should  be  cut  away  as  shown  in  Fig.  23,  or  if  the  fracture  is 


Fig.  22  Fig.  23  Fig.  24 

at  a  greater  angle,  the  surface  may  be  stepped,  as  in  Fig.  24.  This  method  of  prep- 
aration will  be  much  less  conspicuous  than  wliere  the  margin  is  at  an  angle. 

Porcelain  "tips"  are  very  disappointing  in  many  cases,  especially  where  they 
involve  the  entire  incisal  edge.  We  may  have  a  perfect  match  for  the  color  before 
cementing,  and  there  may  be  no  apparent  change  in  the  color  of  the  porcelain  after 
cementing  to  place,  but  the  shadow  caused  by  the  tip  and  cement  will  cause  the  re- 
maining portion  of  the  tooth  to  turn  dark  and  be  decidedly  unsatisfactory  during 
ordinary  conversation.  If  there  is  an  approximal  cavity  which  can  be  included  in 
the  restoration,  this  trouble  does  not  seem  to  appear. 

In  large  cases,  involving  more  than  the  incisal  third,  it  is  preferable  to  follow 
the  method  suggested  for  badly  atrophied  teeth. 

The  retention  for  fracture  cavities  may  be  formed  by  cutting  away  the  dentine 
to  a  depth  eciual  to  the  extent  of  the  fracture,  as  in  Fig.  25,  This  extension  for  the 
retention  is  done  with  an  inverted  cone  bur,  followed  with  a  smooth  fissure  and  all 
walls  should  be  parallel  to  each  other. 

In  cases  where  there  is  danger  of  encroaching  upon  the  pulp  by  using  the  above 
method,  the  procedure  may  be  reversed,  the  enamel  and  a  small  portion  of  the  dentine 


PORCELAIN  AND  GOLD  INLAYS 


171 


removed,  as  in  Fig.  26.  If  tiiese  methods  do  not  seem  to  give  sufficient  anchorage, 
or  the  tooth  is  broken  well  up  on  the  lingual,  the  cavity  should  be  extended  sufficiently 
on  the  lingual  to  gain  the  required  retention,  Fig.  27. 


Fig.  25 


Fig.  26 


With  the  exception  of  very  large,  thick  restorations,  pins  are  contra-indicated  as 
they  so  weaken  the  porcelain  that  it  is  sure  to  fracture  at  this  point. 

In  atrophied  teeth  the  labial  margins  should  be  extended  gingivally  sufficiently 
to  reach  the  normal  contour  of  the  tooth,  otherwise  the  inlay  will  be  noticeable. 
If  this  extension  does  not  go  beyond  the  incisal  third  the  retention  may  be  formed 
the  same  as  in  fractures.  If  the  defect  is  in  the  middle  third  of  the  tooth,  it  is 
advisable  to  remove  the  entire  labial  surface  on  account  of  the  objectionable  changes 
of  the  gingival  third.  First  remove  the  enamel  with  carborundum  stones,  then  shape 
with  inverted  cone  burs,  extending  it  to  the  free  margin  of  the  gums  and  well  to  the 


mesial  and  distal.  Fig.  28  (mesial)  Fig.  29  (distal).  The  porcelain  should  form  the 
contact  point  with  the  approximating  teeth,  otherwise  there  would  be  danger  of 
recurrence   of  decay. 

THE    MATRIX 

Both  platinum  and  gold  foils  have  their  advantage  as  a  matrix  material.  While 
gold  can  be  used  only  for  low  fusing  porcelains,  it  has  the  advantage  of  close  adap- 
tation to  the  margins  of  the  cavity,  thus  makinga  better  fitting  inlay  with  less  burnish- 
ing.    It  has  the  disadvantage  of  becoming  very  soft  when  subjected  to  the  heat  of 


172 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


the  furnace,  thus  necessitating  the  careful  investing  of  the  matrix  before  baking. 
For  this  reason  platinum  is  becoming  more  popular  daily.  There  are  three  thick- 
nesses of  platinum  foil  upon  the  market  ordinarily,  1-1000,  1-1200  and  1-2000.  The 
thicker  foils  are  more  commonly  used,  the  1-1200  being  preferable  to  the  1-1000. 
This  foil  is  slightly  thinner  and  is  sufficiently  rigid  to  withstand  the  manipulating  of 
the  porcelain  without  changing  the  shape. 

It  is  not  necessary  to  anneal  platinum  foil  before  using.  .As  a  rule  it  is  much 
softer  as  it  comes  from  the  manufacturer  than  we  can  possibly  make  it  without 
subjecting  it  to  high  temperatures  in  the  furnace. 

GINGIVAL   CAVITIES 

If  we  have  prepared  our  cavity  afler  the  lines  previously  suggested  it 
will  be  found  to  be  very  difficult  to  force  the  matrix  to  the  bottom  of  the  cavity 
without  tearing.  To  facilitate  matters  it  is  an  excellent  plan  to  first  shape  an  orange 
wood  stick  to  loosely  fit  the  cavity,  as  shown  in  Fig.  30.     Over  this  the  platinum  is 


Fig.  30 


Fig.  31 


roughly  formed.  Fig.  31,  care  being  taken  to  avoid  large  folds  in  the  foil.  If  the  stick 
has  not  been  too  large  I  he  foil  will  drop  to  the  bottom  of  the  cavit}'  without  a  bit  of 
pressure  having  been  brought  to  bear  upon  the  thin  foil.  Next,  place  a  pellet  of 
moist  cotton  in  the  bottom  of  the  matrix  thus  formed  and  with  one  burnisher  hold 
the  matrix  to  place  again.st  the  Hoor  of  the  cavity  while  wii;h  the  other  carefully 
burnish,  starting  at  the  center  of  the  floor  and  gradually  working  towards  the  walls 
of  the  cavity.  At  no  time  allow  the  burnisher  to  touch  the  platinum,  always  have  an 
intervening  cushion  of  damp  cotton.  The  matrix  should  he  adapted  to  every  portion 
of  the  floor  of  the  cavity  before  any  attempt  is  made  towards  the  walls  or  margins. 
The  final  burnishing  is  done  along  the  margins  and  on  the  surface  of  the  tooth. 

At  first  thought  you  would  think  the  folds,  formed  in  shaping  the  matrix  over 
the  stick,  would  remain  in  the  finished  matrix;  however,  if  it  is  carefully  done  every 
one  will  disappear  as  the  burnishing  proceeds. 

After  the  burnishing  is  completed  the  matrix  should  be  packed  full  of  camphor 
gum  (Dr.  Allen)  letting  it  extend  slightly  beyond  the  margins.  This  will  tend  to 
remove  any  rocking  that  may  be  present.  After  teasing  the  matrix  from  the  cavity, 
the  camphor  may  be  burned  away,  leaving  the  matrix  clean  and  in  normal  shape. 


PORCELAIN  AND  GOLD  INLAYS  173 

SIMPLE   APPROXIMAL   CAVITIES 

The  orange  wood  stick  is  equally  of  value  in  these,  as  it  was  in  the  gingival 

cavities.     In  the  first  case  the  end  of  the  stick  was  fitted  to  the  cavity,  while  in  this 

the  side  is  used,  as  in  Fig.  32.     The  platinum  is  shaped  over  one  side,  the  two  edges 

and  the  end  of  the  stick,  as  in  Fig.  33.     On  account  of  the  approximating  tooth  it 


Fig.  32  Fig.  33  Fig.  34 

is  necessary  to  bend  the  edges  of  the  platinum  forming  a  flange  around  the  matrix. 
In  this  manner  the  matrix  readily  goes  to  place  even  though  there  is  but  little  sepa- 
ration, Fig.  34.  The  matrix  is  then  filled  with  damp  cotton  and  burnished  to  place, 
starting  at  the  deepest  part  of  the  cavity  and  graduallj^  working  towards  the  margins. 
After  this  is  accomplished  any  rocking  of  the  matrix  may  be  removed  by  stretching 
damp  English  twill  tape  tightly  over  che  matrix,  or  better  still,  u.=e  a  heavy  rubber 


Fig.  35  Fig.  36  Fig.  37 

band,  stretching  this  over  the  entire  matrix  and  burnishing  over  this  sufficiently  to 
bring  the  platinum  finally  against  the  tooth. 

If  it  is  necessary  to  trim  the  matrix  that  it  may  be  removed  easily,  it  should 
be  done  before  the  final  burnishing,  then  replaced  and  burnished,  using  the  rubber 
band. 


174 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


CAVITIES    INVOLVING    THE    INCISAL    EDGE 

Ordinarily  the  most  difficult  matrix  to  form  without  tearing,  is  one  for  step 
cavities  But  by  carefully  carrying  out  the  following  instructions  it  will  be  found 
very  simple  and  in  the  step  where  folds  are  so  annoying  there  will  not  be  a  wrinkle. 

In  shaping  the  orange  wood  stick,  one  side,  the  end  and  one  edge  are  used,  as 
in  Fig.  35.  Over  this  the  platinum  is  shaped,  as  in  Fig.  36,  again  bending  the  edge 
of  the  platinum  back  in  the  form  of  a  flange  in  order  that  it  may  pass  freely  between 
the  teeth. 

Place  in  the  cavity  and  pack  with  cotton  and  burnish  carefully  into  the  deep 
portion  of  the  cavity,  being  careful  not  to  permit  the  platinum  folding  over  on  the 
labial  surface.  It  should  stand  perfectly  parallel  with  the  labial  margin.  With  a 
pair  of  cotton  pliers  gradually  bend  the  matrix  into  the  step,  Fig.  37.  With  a  flat 
burnisher  adapt  closely  to  the  labial  wall  and  in  the  step,  then  with  the  same  burnisher 


Fig.  38 


Fig.  39 


Fig.  40 


carry  the  surplus  on  the  labial  wall  to  place,  Fig.  38.  Next  carry  the  approximal 
portion  of  the  step  to  place.  Fig.  39,  and  finally  fold  back  the  portion  covering  the 
gingival  of  the  step.  Fig.  40.  This  fold  in  the  platinum  stops  at  the  cavo-surface 
angle,  consequently  it  does  not  interfere  with  the  adaptation  of  the  inlay.  Burnish 
over  the  lingual  margin  carefully  and  use  the  rubber  band  as  in  the  preceding  case. 

EQUIPMENT 

.Before  taking  up  the  manipulation  of  the  porcelain,  I  wish  to  say  a  word  in  regard 
to  the  nece-ssary  equipment. 

It  will  be  noticed  that  very  few  burnishers  were  mentioned  in  the  making  of  the 
matrix.  There  are  several  sets,  of  from  ten  to  fifteen  instruments  each,  upon  the 
market.  These  are  good,  but  an  unnecessary  expense  to  the  man  who  does  not 
expect  to  make  a  specialty  of  porcelain,  and  even  if  he  has  this  in  mind,  he  has 
di.scarded  all  but  one  or  two  before  he  reaches  the  point  to  be  called  a  Specialist. 
The  writer  .seldom  uses  anything  but  the  S.  S.  W.  amalgam  burnishers  Nos.  33  and 
34.  In  these  we  have  two  sizes  of  ball  burnishers,  two  flat  burnishers,  the  edge  of 
which  also  works  very  nicely  to  draw  the  matrix  into  the  angles  of  the  cavity,  and 
the  angle  between  the  ball  of  the  burnisher  and  the  shank  makes  a  very  good  sub- 
stitute for  the  notched  burnisher  commonly  used  to  burnish  over  the  cavo-surface 


PORCELAIN  AND  GOLD  INLAYS 


175 


angle  of  the  cavity.  Thus  the  two  instruments  are  really  equivalent  to  six.  Besides 
the  two  burnishers,  the  only  instruments  used  were  a  pair  of  locking  pliers  and  a  pair 
of  small  shears  for  trimming  the  matrix. 

In  buying  a  supply  of  porcelain  it  is  well  to  procure  the  whole  set  of  colors,  even 
though  some  of  them  are  seldom  used. 

The  selection  of  a  furnace  depends  entirely  upon  the  operator's  surroundings. 
If  he  is  located  where  there  is  nothing  but  a  night  current  of  electricity,  or  no  current 
at  all,  he  will  have  to  get  along  with  a  gasoline  furnace.  While,  if  there  is  a  day 
current,  he  should  not  stop  short  of  an  electric  furnace  with  a  pyrometer  attach- 
ment. The  time  is  coming  when  a  man  will  be  just  as  much  out  of  place  with  a 
furnace  without  a  pyrometer  as  he  would  be  with  a  vulcanizer  without  a  ther- 
mometer. 

The  proper  baking  of  porcelain  should  not  be  underestimated.  Many  a  good 
inlay  has  been  ruined  because  the  dentist  thought  he  could  time  his  furnace  or  tell 
by  the  glow  of  the  muffle. 

If  you  have  no  day  current  you  can  get  very  satisfactory  results  with  the  use  of 
a  device  designed  by  the  writer  after  the  suggestion  of  Dr.  Woodbury,  of  Council 
Blufifs,  Iowa.     Obtain  a  soapstone  crayon  from  a  book  store  or  a  dealer  in  metal 


Fig.  41 

worker's  supplies.  Take  a  piece  two  and  one-half  inches  long  and  shape  as  in  Fig. 
41.  At  "A"  it  is  simply  made  smaller  to  make  a  more  convenient  place  to  get  a 
hold  with  tongs  in  putting  in  and  removing  from  the  furnace.  From  "B"  to  "D" 
it  is  hollowed  out  about  1-16  of  an  inch  to  prevent  the  gold  dropping  into  the  furnace. 
"  C  "  is  a  series  of  small  depressions  made  with  a  large  size  cherry  bur.  These  should 
be  as  close  together  as  possible  without  running  into  each  other.  "E"  is  a  hole 
extending  almost  through  the  block  and  is  used  for  holding  crowns  while  baking,  and 
also  acts  as  a  "center"  for  placing  the  inlay.  As  all  gasoline  muffles  are  hotter  in 
the  rear  than  in  the  front  there  is  a  certain  point,  between  "E"  and  "D,"  at  which 
the  pure  gold  will  melt,  exactly  the  same  time  that  a  higher  fusing  porcelain  reaches 
a  proper  bake,  when  placed  directly  over  "E,"  which  is  in  a  hotter  portion  of  the 
muffle.  Pure  gold  should  always  be  used  and  by  a  little  experimenting  one  can 
regulate  his  pyrometer  by  shifting  the  pellet  of  gold  from  one  hole  to  another  so  that 
he  may  get  any  kind  of  a  bake  he  desires,  from  a  biscuit  to  a  high  glaze.  The  inlay 
should  be  placed  at  exactly  the  same  spot  each  time  and  the  slab  placed  in  the 
muffle  exactly  the  same  distance  each  time.  A  mica  door  should  be  used  and  the 
slab  and  work  should  be  removed  just  as  soon  as  the  gold  is  seen  to  melt.  The  same 
device  will  work  in  electric  furnaces,  but  not  so  well,  as  the  heat  is  more  uniform 
throughout  the  muffle. 

SELECTING   THE   COLORS 

Many  methods  have  been  used  in  building  up  the  colors  for  an  inlay.  A  popular 
method  is  to  select  at  least  three  colors,  one  for  the  gingival  third,  one  for  the  middle 
third,  and  another  for  the  incisal  third. 


176 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


Although  we  are  dealing  with  a  substance  entirely  different  from  the  tooth 
structure,  I  believe  the  best  results  can  be  obtained  only  by  following  Nature's 
scheme.  In  this  manner  there  is  a  gradual  shading  from  the  brownish  yellow  neck 
to  the  blue  tip. 

We  will  first  consider  the  anatomy  of  a  tooth.  From  a  practical  standpoint 
all  dentine  (unless  artificially  stained)  is  the  same  color,  namely,  a  brownish  yellow, 
and  all  enamel  is  blue.  If  this  one  point  is  remembered  by  the  beginner,  three- 
fourths  of  his  trouble  will  be  eliminated.  It  is  so  common  to  find  a  man  trying  to 
use  every  color  in  the  outfit,  when  in  reality  two  or  three  colors  properly  applied  will 
meet  almost  every  requiremant,  except  in  discolored  teeth. 

A  longitudinal  section  of  a  tooth  will  clearly  show  the  relation  of  the  enamel 
and  dentine,  Figs.  42-43.  It  will  be  noticed  that  the  enamel  at  the  neck  is  thin  and 
the  dentine  predominates  decidedly,  while  at  the  tip  the  enamel  predominates.  As 
the  dentine  is  of  a  brownish  yellow  color  and  there  is  very  little  blue  enamel  covering 
it  in  the  gingival  third,  naturally  the  tooth  would  have  the  color  of  the  dentine,  while 


Fig.  42  Fig.  43 

at  the  tip,  where  there  is  practically  no  dentine,  it  would  take  the  color  of  the  enamel, 
and  in  the  middle  third,  where  the  dentine  and  enamel  are  more  nearly  equal,  we 
find  a  composite  of  the  two  colors,  or  a  greenish  gray. 

To  prove  that  it  is  a  difference  in  quantity  of  dentine  and  enamel,  and  the 
relative  proportions  of  each  that  gives  us  the  various  shades  in  teeth,  rather  than  a 
difference  in  coloring  matter,  examine  a  few  of  the  patients  who  present  themselves. 

Patient  A ,  we  will  say,  has  a  decidedly  yellow  tooth.     On  examination  we  will 

find  the  crowns  are  short  and  labio-lingually  they  are  very  thick.     The  dentine 

extending  to  the  cutting  edge,  Fig.  42.     Patient  B has  a  light  blue  tooth;  here 

we  find  a  much  thinner  tooth  labio-lingually.  Fig.  43,  the  labial  and  lingual  plates 
of  enamel  come  almost  together  in  the  middle  third,  consequently  the  tooth  is 
light  and  receives  most  of  its  color  from  the  enamel. 

In  selecting  the  color  of  a  tooth,  get  the  shade  of  the  dentine  as  near  the  gingival 
as  possible  where  the  enamel  is  the  thinnest,  and  select  the  enamel  at  the  very  tip, 
where  it  is  free  from  dentine.     Always  cover  the  shade  guide  with  a  finger,  except 


PORCELAIN  AND  GOLD  INLAYS  177 

an  amount  in  proportion  to  the  tooth.  As  a  matter  of  convenience,  the  series  of 
shades  should  be  grouped  together,  ranging  from  light  to  dark.  This  makes  the 
selection  much  easier.  The  normal  dentine  colors,  in  the  leading  makes  of  porcelain, 
ranging  from  light  to  dark,  are  as  follows: 

White's  High  Fusing:     T,  R,  P,  I,  H,  J,  K. 

Brewster's  High  Fusing:     A,  B,  C,  D,  E,  F,  G,  H. 

Consolidated  High  Fusing:     B,  C,  D.  I,  J,  K,  L,  M. 

Whiteley's  Inlay  Porcelain:     3,  4,  5,  6,  7,  8,  23,  24. 

Brewster's  Gold  Matri.x:     1,  2,  3. 

Jenkin's  Porcelain  Enamels:     22,  20,  17,  4,  7,  27,  12 

Brewster's  Low  Fusing:     1,  2,  3,  4. 

The  colors  of  the  enamels  are: 

White's  High  Fusing:     E,  C. 

Brewster's  High  Fusing:     T;  occasionally  U. 

Consolidated  High  Fusing:     S,  T. 

Whiteley's  Inlay:     13. 

Brewster's  Gold  Matrix:     10. 

Jenkin's  Porcelain  Enamels:     5,  25. 

Brewster's  Low  Fusing:     11. 

There  is  no  rule  in  the  selection  of  colors  for  discolored  teeth.  The  discoloration 
is  always  in  the  dentine  and  may  be  a  decided  brown,  or  a  dark  blue,  or  a  combination 
of  the  two. 

In  selecting  the  color  for  the  dentine  we  may  find  the  color  between  two  shades 
upon  the  ring;  if  this  is  the  case  always  select  the  tlarker  shade — for  example,  if  we 
were  using  S.  S.  W.  high  fusing  porcelain  and  find  "I"  a  little  light  and  "H"  a  little 
dark,  use  "H."  It  is  seldom  necessary  to  use  more  than  one  shade  for  reproducing 
enamel. 

APPLYING   COLORS 

In  the  high  fusing  porcelains  it  is  advisable  to  first  use  a  porcelain  of  different 
density,  as  the  translucency  of  these  porcelains  is  so  great  that  if  we  should  use  the 
sa-ne  porcelain  throughout,  we  would  have  considerable  trouble  from  shadows 
and  cement,  changing  the  color  of  an  inlay.  This  porcelain,  commonly  known  as 
foundation  body,  should  be  slightly  higher  fusing  and  of  different  refracting  proper- 
ties. It  is  not  necessary,  as  some  think,  that  this  should  be  of  a  different  color.  On 
the  other  hand,  better  results  can  be  obtained  easier  by  using  a  foundation  body  of 
a  color  more  nearly  resembling  the  dentine. 

We  will  first  consider  the  building  of  the  colors  for  a  gingival  cavity.  After 
removing  the  matrix  from  the  cavity,  grasp  it  in  a  pair  of  pliers  at  some  point  where 
there  is  an  excess  of  platinum. 

Take  a  small  portion  of  the  yellow  foundation  porcelain  upon  a  glass  slab  and 
mix  with  just  enough  water  to  make  a  doughy  mass.  There  should  be  no  excess  of 
moisture  standing  upon  the  surface.  A  good  way  of  knowing  when  the  mix  is  just 
right  is  to  pass  the  edge  of  the  spatula  through  the  mass;  if  the  halves  do  not  flow 
back  together  or  break  in  cutting,  the  proportions  of  water  and  porcelain  are  correct 
Take  a  small  amount  of  the  porcelain  upon  the  point  of  the  spatula  and  place  in  the 
bottom  of  the  matrix,  then  with  the  gnarled  portion  of  the  handle,  jar  to  place.  An 
excess  of  moisture,  or  too  much  jarring,  will  have  a  tendency  to  separate  the  particles 
of  porcelain,  the  heavier  going  to  the  bottom,  leaving  lighter  on  the  surface,  thus 


178 


PRACTICAL   MANUAL   OF    DENTAL    CASTING 


ruining  the  quality  of  the  finished  porcelain.  Just  as  soon  as  an  excess  of  moisture 
appears  upon  the  surface  it  should  be  removed  either  by  bits  of  blotting  paper  or 
by  touching  the  damp  porcelain  to  the  dry  powder,  then  removing  any  that  may 
stick  with  a  dry  camel's  hair  brush.  This  foundation  porcelain  should  in  no  case 
come  to  the  margins  of  the  cavity,  but  should  be  built  only  to  within  about  a  milli- 
meter of  the  surface,  as  shown  in  Fig.  44.  It  is  not  necessary  to  use  any  scheme  to 
direct  the  shrinkage,  such  as  cutting  crosses  in  the  porcelain,  varnishing  the  matrix, 
etc.,  as  even  if  the  matrix  does  change,  we  have  an  opportunity  of  reburnishing, 
as  we  left  all  our  margins  free.     This  should  be  baked  to  a  low  glaze. 


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Fig.  45 


Fig.  46 


After  reburnishing,  grasp  the  matrix  in  locking  pliers  and  take  a  small  quantity 
of  the  porcelain  selected  to  restore  the  dentine  and  carefully  fill  the  crevices  caused 
by  the  shrinkage  of  the  foundation  body.  Then  add  enough  of  the  dentine  porce- 
lain to  reproduce  che  dentine  of  the  tooth.  Great  care  should  be  taken  in  placing 
this  porcelain,  as  just  the  right  amount  of  space  should  be  left  for  the  overlying 
enamels.  The  dentine  porcelain  should  be  carried  to  the  surface  at  the  gingival, 
receding  gradually  as  the  incisal  is  approached.  Fig.  45.  If  the  shrinkage  is  ex- 
cessive a  second  bake  may  be  necessary.  This  should  also  be  baked  to  a  low  glaze, 
and,  in  fact,  every  bake  until  the  last,  otherwise  the  porcelain  would  be  overbaked 
on  the  finish.  Next,  restore  the  enamel  with  the  blue  porcelain.  Fig.  46,  never 
building  it  beyond  the  margins,  as  the  amount  of  shrinkage  is  verj'  uncertain.  If  the 
shrinkage  brings  the  surface  below  the  proper  contour,  add  sufficient  to  restore  the 
shrinkage. 

Do  not  try  to  make  inlays  in  a  hurry.  If  a  few  extra  bakes  will  give  a  better 
result,  do  not  try  to  do  it  all  in  one. 

The  same  scheme  of  building  colors,  as  illustrated  for  gingival  cavities,  is  used 
for  simple  approximal  cavities. 


PORCELAIN  AND  GOLD  INLAYS 


179 


In  Fig.  46  you  will  notice  the  manner  of  building  up  the  foundation  porcelain. 
As  before,  the  margins  are  kept  entirely  free,  thus  preventing  a  change  in  the  matrix 
in  this  region  and  enabling  the  operator  to  reburnish  if  he  feels  in  doubt  of  his  adapta- 
tion. Fig.  47  shows  the  restoration  of  the  dentine.  If  the  cavity  is  large  and  the 
gingival  margin  extends  to  the  neck  of  the  tooth,  this  porcelain  is  built  quite  to  the 
surface,  receding  as  it  approaches  the  incisal  margin.  It  will  be  noticed  that  both 
the  labial  and  the  lingual  surfaces  are  trimmed  away  about  equally.  This  was  done 
simply  for  the  pleasing  effect  if  examined  on  the  lingual.  However,  the  writer  often 
thinks  it  prevents,  to  a  large  extent,  the  change  in  the  inlay,  from  shadows.  It 
may  be  necessary  to  apply  this  dentine  portion  the  second  time  to  compensate  for 
the  shrinkage.  On  this  the  enamel  porcelain  is  built,  bringing  it  just  flush  with  the 
margins.  This  will  necessitate  a  second  baking,  but  it  is  difficult  to  judge  shrinkage 
and  it  also  gives  one  an  opportunity  of  making  a  slight  change  in  the  colors  if  his  first 
selection  was  not  correct. 


Fig.  46 


Fig.  47 


In  cavities  of  the  third  class,  the  foundation  body  is  carried  only  to  within  about 
a  millimeter  and  one-half  of  the  incisal  edge.  Fig.  48.  The  dentine  porcelain  may 
stop  about  the  same  point  or  extend  entirely  to  the  cutting  edge,  depending  entirely 
upon  the  labio-lingual  diameter  of  the  tooth.  As  a  rule  we  will  find  it  necessary  to 
extend  the  dentine  quite  to  the  surface  at  the  gingival,  Fig.  49,  as  we  select  the  dentine 
where  it  is  modified  to  a  certain  extent  by  the  enamel  and  do  not  get  the  true  dentine 
color. 

In  all  cases  be  particular  to  restore  the  contour  of  the  dentine  as  it  originally 
was  in  the  tooth.  Fig.  50.  The  enamel  is  contoured  exactly  as  you  wish  the  finished 
inlay  and  just  flush  with  the  margins.  Never  guess  at  an  excess  which  will  compen- 
sate for  the  shrinkage,  as  there  is  no  fi.xed  rule  regarding  the  amount  of  shrinkage 
and  the  less  we  use  a  stone  in  finishing  our  inlay  the  better  the  result. 

Before  taking  up  the  next  step,  it  may  be  well  to  mention  a  few  precautions, 
helps,  etc.,  in  the  working  of  the  porcelain.  Never  lay  the  matrix  down,  but  grasp 
it  in  a  pair  of  pliers  and  lay  the  pliers  so  that  the  inlay  will  stand  out  from  the  edge 
of  the  table. 

Distilled  water  is  preferable  to  alcohol  for  mixing  all  porcelains,  as  it  evaporates 
more  slowly  allowing  ample  time  for  carving  the  porcelain.     Do  not  try  to  work  the 


180 


PRACTICAL   MANUAL   OF    DENTAL    CASTING 


porcelain  too  damp,  as  it  is  impossible  to  build  contours,  and  the  porcelain  ingredients 
have  a  tendency  to  separate,  thus  producing  a  weak  product. 

It  is  seldom  necessary  to  mix  colors.  Get  shades  by  laying  one  color  over 
another.  Never  attempt  to  build  in  the  enamel  color  without  having  first  baked 
the  dentine  color  to  a  low  glaze,  as  the  colors  will  blend  and  produce  an  entirely 
different  result.  In  removing  an  excess  of  moisture,  the  best  absorbent  is  the  dry 
porcelain  powder  which  is  being  used  at  the  time.  Touch  the  inlay  to  the  dry  powder, 
then  brush  away  the  adhering  particles  with  a  soft  dry  camel's  hair  brush.  Never 
use  a  damp  brush  to  remove  the  excess  of  porcelain  on  the  margins  of  the  matrix, 
it  simply  makes  a  thinner  layer  of  the  porcelain  and  makes  it  difficult  to  remove. 
A  better  way  is  to  loosen  the  particles  of  the  body  with  the  point  of  the  carving  in- 


Fig.  48 


Fig.  49 


Fig.  50 


strument  and  brush  away  with  a  dry  brush.  Remember  that  low  fusing  porcelains 
are  more  nearly  opaque  than  the  high  fusing,  consequently  it  is  necessary  to  carry 
the  dentine  color  to  the  surface  of  the  inlay.  Otherwise  the  enamel  color  will  cut 
it  out  completely. 

Before  baking,  always  examine  the  under  or  cavity  surface  of  the  matrix  to 
make  sure  there  has  no  porcelain  run  over  on  that  side.  If  there  has,  it  should  be 
removed  before  placing  in  the  furnace,  as  it  will  be  impossible  to  remove  the  matrix 
and  will  prevent  the  inlay  going  to  place.  Be  sure  the  porcelain  is  entirely  dry 
before  placing  in  the  hot  furnace.  Do  not  bake  too  rapidly.  A  much  higher  grade 
of  porcelain  will  be  produced  by  starting  with  a  cool  furnace  and  gradually  raising 
the  temperature,  using  plenty  of  time  to  allow  the  heat  to  penetrate  the  body. 
Placing  in  a  hot  furnace  or  raising  the  temperature  too  rapidly  will  cause  a  crust  to 
form  on  the  surface  and  the  inner  part  will  be  porous. 

Do  not  apply  the  body  in  the  center  of  the  inlay  and  expect  it  to  flow  to  the 
margins  by  jarring.  It  may  seem  to  do  this,  but  at  the  final  bake  a  row  of  bubbles 
will  appear  along  the  margins  as  a  result  of  this.  It  is  better  to  build  all  over  the 
surface  to  a  slight  excess,  then  trim  down  to  the  desired  contour. 


PORCELAIN  AND  GOLD  INLAYS 


181 


REMOVING   THE    MATRIX 

After  the  inlay  has  been  properly  baked,  the  next  step  is  to  remove  the  matrix. 
This  should  be  carefully  done  by  grasping  the  free  edge  of  the  platinum  in  a  pair  of 
pliers  and  peeling  toward  the  center.  This  may  be  more  easily  accomplished  bj' 
first  dipping  the  inlay  in  water. 

After  removing  the  matrix  the  cavity  surface  of  the  inlay  must  be  roughened 
to  permit  the  cement  to  properly  adhere.  This  may  best  be  accomplished  by 
imbedding  the  inlay  in  wax,  leaving  only  the  cavity  surface  exposed  and  etch  with 
hydrofluoric  acid.  It  should  be  left  in  the  acid  from  two  to  five  minutes,  depending 
upon  the  porcelain  and  the  strength  of  the  acid.  This  is  very  important  and  should 
not  be  neglected.  A  simple  gingival  inlay  with  four  antagonizing  walls  will  not  hold 
if  it  is  not  properly  roughened. 

The  acid  should  be  thoroughly  removed  by  washing,  using  a  fine,  stiff"  brush. 


Figs.  51-52 


SETTING   THE   INLAY 

The  so-called  "Cement  Problem"  has  confronted  the  porcelain  worker  for  years. 
A  great  deal  of  the  change  in  color,  on  cementing  an  inlay  to  place,  is  due  to  a  too 
thick  layer  of  cement  between  the  inlay  and  the  cavity.  This  may  be  due  to  lack  of 
adaptation  of  the  inlay,  using  cement  so  thick  that  the  inlay  fails  to  go  to  place, 
or  having  a  cement  that  is  so  coarsely  ground  that  it  will  not  permit  the  inlaj'  going 
to  place.  The  color  of  the  cement  has  little  to  do  with  it,  a  light  cement  being  nearly 
as  bad  as  a  dark  under  similar  circumstances.  Thin  layers  of  cement  will  transmit 
light;  therefore,  if  we  expect  our  inlays  to  retain  their  color  after  setting,  we  must 
have  our  adaptation  so  perfect  that  the  layer  of  cement  will  be  thin  enough  to  trans- 
mit light. 

No  cement  should  be  used  except  one  which  is  especially  ground  for  inlay  pur- 
poses. The  writer  prefers  a  cement  pearl  gray  in  color.  This  should  be  carefully 
mixed  to  a  creamy  consistency,  being  careful  that  there  is  sufficient  powder  to  take 
up  all  the  free  acid.  This  should  be  spread  over  the  dry  cavity  with  an  explorer, 
using  as  nearly  as  possible  the  exact  amount  necessary.  Force  the  inlay  to  place 
and  keep  under  pressure  until  the  cement  sets.  If  the  work  has  been  properly  done 
there  should  be  little  or  no  grinding  to  do  after  the  inlay  sets. 


182 


PRACTICAL   MANUAL   OF    DENTAL    CASTING 


GOLD    INLAYS 

Probably  nothing  ever  introduced  into  dentistry  was  so  universally  taken  up 
and  created  such  wild  enthusiasm  as  did  the  gold  inlay,  when  Dr.  Taggart  introduced 
the  casting  process.  There  was  scarcely  a  practitioner,  no  matter  from  how  remote 
a  corner  of  the  land  he  came,  who  had  not  adopted  the  process  within  the  year. 
And  today,  alas,  how  expensive  this  wild  rush  has  been  to  many  a  man's  practice. 
Undoubtedly  greater  care  is  needed  in  making  a  gold  inlay  than  ever  was  called  for 
in  porcelain  restorations.  The  difficulty  in  thoroughly  roughening  the  gold  to  insure 
perfect  adhesion  of  the  cement,  necessitates  a  careful  consideration  of  mechanical 
retention  in  the  cavity. 

Although  the  casting  process  has  decided  advantages  in  most  cases,  there  are 
certain  cases  when  the  old  method  of  burnishing  a  matrix  is  preferable.  While  in 
others  a  combination  of  the  two  will  produce  the  best  results. 

In  small  cavities  with  four  walls,  much  time  can  be  saved  and  an  equally  good 
inlay  made  by  burnishing  a  matrix  of  platinum  and  filling  with  pure  gold.  In  cases 
of  large  size  where  it  is  difficult  to  remove  the  wax  without  impairing  the  margins,  a 
combination  of  a  pure  gold  matrix  and  the  remainder  cast,  is  indicated. 


Figs.  53-54-.55 


STUDY    THE    OCCLUSION 

Before  starting  the  preparation  of  a  cavity  for  a  gold  inlay  a  careful  consideration 
of  the  occlusion  must  be  made.  A  cavity  must  have  a  resistance  form  to  antagonize 
all  stress  upon  the  inlay  or  it  will  surely  be  dislodged.  Have  the  patient  move  the 
jaws  laterally  and  notice  the  stress  in  this  direction,  then  mesio-distally,  as  well  as  at 
rest.  Many  peculiar  conditions  are  brought  out  by  doing  this,  which  may  completely 
change  the  nature  of  the  cavity  preparation. 

CAVITY   PREPARATION 

Simple  Approximal  Cavities 
The  general  outline  of  a  cavity  for  a  gold  inlay  for  simple  cavities  is  very  similar 
to  that  given  for  porcelain.  In  cases  where  the  occlusion  is  normal,  the  lingual  wall 
should  be  cut  away  to  permit  the  removal  of  the  wax  pattern  or  matrix,  in  that 
direction.  The  incisal  and  gingival  walls  should  be  parallel  to  each  other  mesio- 
distally  and  there  should  be  a  decided  seat  under  the  labial  wall.  The  incisal  and 
gingival  walls  should  diverge  slightly  from  labial  to  lingual,  to  permit  the  removal 
of  the  pattern. 


PORCELAIN  AND  GOLD  I  NLA  YS 


183 


The  technic  of  the  operation  consists  of,  first,  breaking  down  an>'  thin  enamel 
margins  and  cutting  away  the  Ungual  wall  with  chisels,  always  remembering  that 
unless  enamel  has  an  underlying  support  of  dentine,  it  is  worthless  and  should  be 
removed.  Next,  with  a  smooth  square-end  fissure  bur  in  a  right  angle,  entering 
from  the  lingual,  extend  the  gingival  margin  sufificiently  to  permit  the  removal  of  the 
pattern.  Form  the  incisal  wall  in  the  same  manner,  and  with  the  square  end  of  the 
bur  cut  the  seat  under  the  labial  wall.  Then,  with  hatchet  and  hoe  excavators 
make  a  definite  angle  at  the  junction  of  the  incisal,  gingival  and  labial  walls  with  the 
axial.  In  very  deep  cavities  it  is  well  to  build  in  with  cement,  care  being  taken  not 
to  carry  it  to  an  extreme.     All  margins  should  be  smooth  and  slightly  beveled. 

CAVITIES    INVOLVING   THE   INCISAL   ANGLE 

In  this  class  of  cavities  it  is  preferable  to  use  a  step  for  incisal  retention.  In 
cutting  this,  fine  grit  carborundum  stones  are  used,  extending  it  sufficiently  laterally 
to  permit  making  a  pit  in  perfectly  sound  dentine.  On  the  labial,  only  sufficient 
should  be  cut  away  to  give  the  enamel  a  protection  of  gold.  Much  less  cutting  is 
necessary  as  compared  with  that  for  a  gold  filling. 


57 

Figs.  .56-57-58 

The  lingual  wall  of  the  step  should  be  cut  away  to  permit  good  anchorage  in 
dentine.     At  the  end  of  the  step  should  be  a  well  defined  pit. 

The  body  of  the  cavity  is  prepared  much  the  same  as  that  for  porcelain,  cutting 
away  the  lingual  to  permit  the  easy  removal  of  the  pattern.  The  gingival  wall 
should  be  flat  and  there  should  be  a  flat  seat  under  the  labial  plate.  In  deep  cavities 
the  axial  wall  may  be  built  out  with  cement,  care  being  taken  that  all  margins  are 
freed  from  cement  before  the  impression  is  taken. 

CAVITIES   IN   BICUSPIDS    AND   MOLARS 

The  ideal  place  for  gold  inlays  is  in  the  bicuspids  and  molars.  They  eliminate 
the  great  difficulty  of  placing  cohesive  gold  in  inaccessible  cavities  and  have  greater 
strength.  Within  a  very  short  time  the  inlay  will  almost  take  the  place  of  the  gold 
crown.     The  misfitting  band  and  inflamed  gum  will  be  a  thing  of  the  past. 

In  all  proximal  cavities  in  bicuspids  and  molars  there  should  be  a  step  including 
all  fissures  on  the  occlusal  surface. 

Figs.  56,  57  and  58  represent  a  cavity  in  the  bicuspid.  In  the  proximal  portion 
there  should  be  a  flat  gingival  seat,  the  buccal  and  lingual  walls  should  be  as  near 
parallel  to  each  other  as  possible  and  permit  the  removal  of  the  impression.     The 


184 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


occlusal  portion  should  be  of  sufficient  width  and  depth  to  give  strength  to  the  inlay 
and  should  terminate  in  a  definite  dove-tail  which  affords  retention  from  dislodgment 
approximall}'.  In  badly  decayed  teeth,  the  cavity  should  be  built  out  with  cement, 
to  within  a  millimeter  and  a  half  of  the  surface.  This  will  give  sufficient  bulk  of  gold 
and  will  make  the  inlay  of  better  retention  form. 

In  larger  cases,  especially  where  both  mesial  and  distal  surfaces  are  involved, 
and  the  buccal  and  lingual  walls  are  weak,  the  cusps  should  be  removed  and  the  tip 
restored  with  gold. 

Molar  cavities,  Fig.  59,  are  prepared  along  the  same  lines,  making  an  occlusal 
step  extending  into  all  the  deeper  fissures.  The  pulpal  and  gingival  walls  should  be 
flat  and  at  right  angles  to  stress.  The  buccal  and  lingual  walls  should  be  as  near 
parallel  to  each  other  as  possible  and  permit  the  removal  of  the  pattern. 

All  the  above  cavities  are  for  the  restoration  of  lost  tooth  structure,  and  are  not 
intended  to  carry  lost  teeth  in  bridge  work.  The  cavities  following  are  intended  more 
especially  for  use  in  bridge  work  and  the  retention  of  teeth. 


Fig.  59 


GOLD   INLAYS   FOR    BRIDGE    ABUTMENTS 

The  casting  process  opens  a  field  in  bridge  work  of  inestimable  value.  In  the 
past  many  teeth  have  been  mutilated  for  the  construction  of  bridge  work,  which  in 
the  future  will  be  saved  almost  in  their  entirety  with  the  use  of  inlays.  We  have  all 
experienced  the  difficulty  of  properly  shaping  molars  and  bicuspids  to  permit  a  close 
fitting  shell  crown.  While  in  the  anterior  teeth  it  necessitated  the  use  of  a  shell 
crown  or  the  entire  destruction  of  the  crown  of  the  tooth  for  a  Richmond  crown  to 
permit  of  bridge  work.  With  inlays  a  much  more  sanitary  and  an  equally  strong 
anchorage  may  be  made.  It  is  a  system,  however,  that  will  necessitate  the  greatest 
care  on  the  part  of  the  operator  in  regard  to  every  detail  in  the  preparation  of  the 
cavity  adaption  of  the  inlay  and  attachment  of  the  dummies. 

In  preparing  a  cavity  for  an  abutment  we  should  examine  the  occlusion  minutely 
and  make  a  careful  estimate  of  the  stress  that  will  be  brought  to  bear  upon  the 
restoration.  Always  bear  in  mind  that  there  is  a  certain  amount  of  movement  of 
teeth  in  their  sockets  and  that  the  movement  may  not  be  equal  at  both  ends  of  the 
bridge;  hence  unless  we  have  an  absolute  mechanical  anchorage  the  inlay  will  surely 
be  dislodged. 

We  will  first  consider  the  preparation  of  a  cavity  in  a  cuspid.  In  most  cases  it 
is  advisable  to  devitalize  and  use  an  iridio-platinum  pin  as  anchorage.     After  having 


PORCELAIN  AND  GOLD  INLAYS  185 

removed  the  pulp  and  filled  the  canals,  take  a  carborundum  stone  and  remove  the 
approximo-lingual  angle.  Then  with  inverted  cone  burs  extend  the  proximal 
portion  well  to  the  gingival,  Figs.  60-61-62,  making  a  flat  gingival  seat.  The  ap- 
proximal  portion  of  the  cavity  should  be  extended  labially  sufficiently  to  make  the 
labial  margin  perfectly  self-cleansing  and  at  the  same  time  not  so  far  as  to  show  the 
gold  appreciably.     The  pulpal  wall  of  the  main  portion  of  the  cavity  should  be 


Figs.  60-61-62 

made  flat  and  at  right  angles  to  the  long  axis  of  the  tooth.  The  incisal  edge  should 
be  cut  away  sufficiently  to  permit  its  restoration  with  gold.  In  no  case  should  the 
labial  plate  be  left  standing  without  this  protection.  All  margins  should  be  at  right 
angles  to  the  surface  of  the  tooth  with  a  slight  bevel  of  the  outer  third  of  the  enamel. 
The  root  canal  should  be  enlarged  to  admit  a  16-gauge  iridio-platinum  bar  and  be  a 
depth  equal  at  least  the  length  of  the  crown  of  the  tooth. 


Figs.  63-64-65 

In  cases  for  small  bridges  a  staple  inlay  may  be  used  without  the  necessity  of 
devitalizing,  as  Figs.  63,  64,  65.  The  lingual  plate  of  enamel  is  removed  with  car- 
borundum stones  entirely  to  the  incisal.  Each  approximal  surface  is  prepared 
similar  to  that  described  above.  Then  with  inverted  cone  burs  make  the  lingual 
wall  flat  and  at  right  angles  to  the  surface.  At  the  junction  of  the  middle  and  incisal 
thirds  a  step  is  formed  with  an  inverted  cone  bur.  The  cavity  should  be  extended 
to,  and  include,  the  incisal  edge,  which  should  be  restored  with  gold. 


186 


PRACTICAL    MANUAL   OF    DENTAL    CASTING 


Figs.  66-67-68 

Figs.  66,  67  and  68  represent  a  lateral  incisor  with  an  approximal  preparation 
for  bridge  anchorage.  In  this  case  the  cavity  is  stepped  on  the  incisal  and  an  18- 
gauge  iridio-platinum  pin  extends  into  the  canal  from  the  step.  In  all  cases  the 
important  points  are,  first,  extend  the  cavity  to  self-cleansing  areas;  second,  obtain  a 
thorough  resistance  form,  and  third,  procure  positive  anchorage  from  all  stress. 


Figs.  69-70-71 

In  bicuspids  and  molars  there  should  be  post  anchorage  in  badly  broken  down 
cases.  Where  the  greater  part  of  the  tooth  is  intact,  the  cavities  should  include 
both  mesial  and  distal  surfaces  extending  well  to  the  gingival  on  both  approximal 
surfaces.     Fig.  69. 

Figs.  70  and  71  show  a  badly  broken  down  molar  with  the  pulp  chamber  built 
out  with  cement.  In  these  cases  it  is  important  to  have  flat  gingival  seats  with 
sufficient  breadth  to  withstand  stress.  All  the  cusps  should  be  ground  away  suf- 
ficiently to  protect  them  with  gold. 

FORMING   THE    MATRIX    OR   PATTERN 

In  small  approximal,  pit,  gingival  and  occlusal  cavities,  it  is  much  easier  and 
quicker  many  times  to  use  the  old  method  of  forming  a  platinum  matrix  and  filling 
with  pure  gold,  rather  than  the  new  method  of  casting. 


PORCELAIN  AND  GOLD  INLAYS  187 

Wc  will  take  for  example  a  gingival  cavity.  Here  we  have  the  secretions  of 
the  mouth  to  annoy  us,  as  well  as  the  close  proximity  of  the  gum  margin.  The  wax 
has  a  tendency  to  crumble  under  moisture  and  again  it  is  difficult  to  remove  the  wax 
when  the  cavity  extends  beneath  the  gum.  In  simple  approximal  and  small  occlusal 
cavities  it  is  a  comparatively  simple  matter  to  burnish  a  matrix,  within  a  very  few 
minutes  it  may  be  filled  with  gold  and  ready  for  cementing  to  place  and  finish. 

The  method  preferred  would  be  to  form  an  orange  wood  stick  to  loosely  fit  the 
cavity,  over  this  shape  a  piece  of  1-1000  platinum  foil  as  described  for  a  porcelain 
inlay,  (Figs.  30-31).  Remove  the  matrix  and  place  in  the  cavity  and  burnish  to 
place,  being  careful  to  spread  over  the  floor  of  the  cavity  first,  then  gradually  over 
the  walls  and  margins.  The  excess  may  be  trimmed  almost  entirely  away  along 
the  gingival  margins  if  the  gum  interferes.  Remove  from  the  cavity,  heat  in  a 
flame  until  all  carbon  has  been  burned  off,  cool  and  coat  the  surface  next  to  the 
cavity  with  a  thin  solution  of  chalk  in  alcohol.  Great  care  should  be  used  in  ap- 
plying the  chalk,  not  to  permit  any  to  run  into  the  matrix,  as  it  will  cause  no  end  of 
trouble  in  melting  the  pure  gold.  Allow  the  alcohol  to  evaporate,  then  place 
the  matrix  upon  a  soldering  block  and  fill  about  one-half  with  pure  gold.  Do  not 
use  flux,  as  it  is  unnecessary'  and  causes  pits  in  the  inlay.  Immediately  drop 
the  matrix  into  nitric  acid  which  will  remove  the  chalk.  Place  in  the  cavity  and 
reburnish.  Unless  the  inlay  is  large  the  second  time  the  gold  may  extend  to  the 
surface.  After  cleaning  in  nitric  acid,  roughen  the  surface  with  a  small  bur  and 
cement  to  place.  Before  the  cement  starts  to  cr^'stalize,  burnish  all  margins  care- 
fully. Then  finish  the  same  as  a  filling.  If  there  are  small  tears  in  the  bottom  of 
the  matrix  there  will  be  no  danger  of  the  gold  flowing  through,  if  the  cavity  surface 
is  carefully  coated  with  the  chalk. 

In  large  contour  cases  the  preferable  method  is  to  use  the  casting  process. 
When  this  method  was  introduced,  it  seemed  so  easy  and  simple  that  the  majority 
of  men  rushed  at  it  with  little  thought  of  what  the  probable  outcome  would  be.  There 
is  no  operation  in  dentistry  more  difficult  than  properly  removing  and  investing  a 
wax  pattern.  This  may  seem  a  strange  statement  but  it  is  true,  nevertheless.  In  the 
first  place  the  cavity  should  be  so  prepared  with  parallel  walls  that  there  is  a  certain 
amount  of  frictional  retention  and  if  this  is  done  there  is  considerable  danger  of  dis- 
torting the  pattern  in  removing. 

When  it  comes  to  investing  the  pattern  there  is  great  danger  of  changing  its 
shape. 

THE    WAX    PATTERN 

In  considering  this  step  in  inlay  construction,  it  is  important  that  we  first  con- 
sider the  material  we  are  to  work  with.  There  has  been  almost  as  many  makes  of 
wax  thrust  upon  the  profession  as  there  have  been  casting  machines,  and  the  majority 
are  absolutely  worthless.  The  fact  of  the  matter  is,  our  best  base  plate  waxes  are 
far  superior  to  the  majority  of  inlay  wax  offered  for  sale. 

The  important  feature  in  an  inlay  wax  is  to  have  one  with  the  least  possible 
amount  of  inorganic  material  present.  In  other  words,  one  that  can  be  completely 
destroyed  by  moderate  heat.  The  next  essentials  are,  tenacity,  close  grain  and 
rigidity  when  cool.  The  ideal  wax  should  be  one  that  could  be  softened  and  formed 
in  a  cone  with  dry  heat  and  when  soft  should  work  like  chewing  gum.  When  forced 
into  the  cavity  it  should  not  crack  or  crumble,  but  mold  to  any  form  desired,  either 
with  the  use  of  the  fingers  or  instruments.  After  chilling,  it  should  carve  easily  and 
take  on  a  high  polish. 


188 


PRACTICAL   MANUAL   OF    DENTAL    CASTING 


When  making  the  wax  pattern,  the  tooth  should  be  slightly  moist  to  prevent 
the  wax  sticking.  Warm  the  wax  until  it  is  like  putty,  shape  in  the  form  of  a  cone 
and  force  into  the  cavity  with  the  thumb  and  finger,  compressing  the  wax  as  much  as 
possible  with  the  fingers  to  insure  perfect  adaptation  to  the  walls  of  the  cavity.  In 
approximal  cavities  an  excellent  plan  is  to  use  a  heavy  piece  of  dam,  placing  it  between 
the  teeth,  first  allowing  it  to  rest  against  the  approximating  tooth  until  the  wax  is 
forced  into  the  cavity,  then  with  considerable  tension  upon  the  rubber,  force  the 
wax  to  place  in  the  cavity.  With  flat  burnisher,  working  from  the  center  of  the 
cavity  towards  the  margins,  work  down  smooth  and  at  the  same  time  remove  the 
excess.  The  wax  should  be  as  nearly  as  possible  the  exact  contour  desired  in  the 
finished  inlay,  having  no  more  of  an  excess  over  the  margins  than  the  thickness  of 
paper.  After  getting  as  smooth  as  possible  with  the  burnisher,  polish  with  a  pellet 
of  cotton  or  a  soft  tape  passed  between  the  teeth. 

Great  care  should  be  used  in  the  removal  of  the  pattern.  It  is  best  not  to 
attempt  the  insertion  of  the  sprue  until  the  pattern  has  been  removed,  as  many 
times  it  would  be  impossible  to  attach  at  the  most  advantageous  point.  With  gentle 
pressure  upon  the  labial  and  lingual  surface,  using  a  small  pellet  of  cotton  in  the 
cotton  pliers,  loosen  the  pattern.     The  greatest  care  should  be  used  in  its  handling 


Fig.  72 


after  it  has  been  dislodged,  as  the  margins  are  thin  and  easily  bent  out  of  place.  A 
very  convenient  receptacle  to  allow  the  pattern  to  drop  onto,  from  the  cavity,  is  a 
large  size  mouth  mirror  frame,  one  that  has  the  glass  broken  away  and  replaced  with 
a  thin  layer  of  cotton.  As  soon  as  removed,  the  sprue  should  be  attached  and  the 
pattern  covered  with  a  thin  layer  of  investment  and  should  never  be  permitted  to 
lie  around,  even  in  water,  for  some  future  time  to  invest. 

In  bicuspids  and  molars  after  forcing  the  wax  to  place  in  the  cavity,  have  the 
patient  close  his  teeth  and  move  the  jaws  laterally,  in  order  that  the  occlusal  surface 
may  be  as  nearly  perfect  as  possible.  After  trimming  down  the  approximal  portion 
and  smoothing  as  much  as  possible,  have  the  patient  close  again  to  make  sure  the  wax 
has  not  been  misplaced  in  the  smoothing  process. 

A  careful  examination  of  normally  occluding  teeth  will  show  the  fissures  and 
sulci  of  the  tooth  extend  deeper  than  the  tip  of  the  occluding  tooth.  So  we  should 
carve  the  fissures  slightly  deeper  than  the  impression  made  by  the  occluding  tooth. 
A  very  good  tool  for  this  purpose  is  a  small  pointed  lancet,  or  in  many  cases  the 
ordinary  hook  scaler  is  excellent.  After  shaping  the  occlusal  surface  the  occlusion 
should  be  again  tested  to  make  sure  the  wax  was  not  misplaced  in  carving. 


PORCELAIN  AND  GOLD  INLAYS 


189 


At  this  point  it  might  be  well  to  mention  the  use  of  iridio-platinum  pins  as 
anchorage.  In  many  cases  it  is  not  only  difificult  to  get  the  wax  into  the  pits  but  it  is 
uncertain  about  their  casting  and  lack  of  strength  when  cast,  so  a  much  better 
method  is  the  use  of  pins.  An  iridio-platinum  wire,  about  20  gauge,  is  preferable 
for  incisal  anchorage,  and  16  gauge  for  anchoring  single  inlaw's  in  root  canals.  If  the 
inlay  is  to  be  used  for  bridge  retention,  14  gauge  sprue  wire  should  be  used.     In  getting 


Fig.  73 

the  pattern  for  an  inlay  where  20  gauge  wire  is  to  be  used  for  incisal  retention,  it  is 
best  to  force  the  wax  home  in  the  cavity  first,  then  heat  the  pin  slightly  and  push  it 
through  the  wax  into  the  pit. 

In  using  pins  in  the  canals,  it  is  better  to  shape  the  wax  in  a  cone  around  the 
pin  before  inserting  into  the  cavity,  having  first  shaped  and  bent  the  pin  to  conform 
to  the  cavity  and  canal. 

In  an  inlay  to  be  used  as  an  abutment  for  a  bridge,  a  square  14  or  16  gauge 
iridio-platinum  pin  should  be  used.     The  pin  should  extend  into  the  canal  at  least 


Fig.  74 


the  length  of  the  crown  of  the  tooth,  and  should  be  bent  at  right  angles  and  extend 
beyond  the  contour  of  the  tooth  sufficiently  to  insure  thorough  union  with  the 
dummies  of  the  bridge. 

The  writer  does  not  believe  a  soldered  union  direct  with  an  inlay  is  good  practice. 
In  the  first  place  our  solders  lack  strength  and  consequently  in  order  to  get  sufficient 
strength  it  is  necessary  to  use  such  a  large  quantity  of  solder  that  we  have  destroyed 
our  self-cleansing  margins.  By  using  the  heavy  iridio-platinum  union,  all  margins 
can  be  made  self-cleansing  without  weakening  the  bridge.     If  we  are  using  a  vital 


190  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

tooth  as  an  abutment,  it  is  a  question  in  the  writer's  mind  if  it  is  good  practice  to 
attach  the  inlay  direct  to  the  bridge,  unless  the  extension  is  very  large.  A  simple 
approximo-occlusal  cavity  in  a  bicuspid  should  never  be  used  in  this  way.  If  the 
cavity  is  a  mesio-occluso-distal,  it  may  prove  satisfactory,  but  the  inlay  should  always 
be  constructed  with  the  use  of  an  iridio-platinum  wire,  as  shown  in  Fig.  75. 

If  a  simple  approximo-occlusal  inlay  is  used  for  anchorage  it  is  not  well  to  make 
a  solid  union  to  the  bridge,  but  instead,  the  iridio-platinum  bar  should  rest  within  a 
tube  and  set  in  the  inlay.  This  is  easily  formed  by  shaping  a  piece  of  platinum  plate  over 
the  wire  to  be  used,  and  this  set  in  the  wax  in  the  region  of  the  contact  point.  This 
method  allows  a  certain  amount  of  movement  which  is  always  present  during  mastica- 
tion, and  prevents  dislodgment  of  the  inlay. 


Fig.  75 

In  attaching  the  sprue,  care  should  be  taken  to  attach  at  such  a  point  that  the 
gold  will  be  forced  as  near  as  possible  towards  all  margins  of  the  inlay.  If  this  pre- 
caution is  taken  the  defects,  if  any,  will  not  be  at  the  margins  but  some  place  upon 
the  surface  of  the  inlay  where  it  can  be  more  easily  repaired. 

INVESTMENTS   AND    INVESTING 

This  particular  phase  of  inlay  work  does  not  receive  the  attention  it  should. 
In  the  first  place  the  wax  pattern  should  be  so  carefully  made  and  polished  over  the 
surface  that  it  is  without  a  flaw,  then  secondly,  it  should  be  invested  with  an  invest- 
ing material  that  will  conform  to  the  pattern  and  produce  a  casting  as  perfect  as  the 
original  pattern.  Our  neglect  lies  in  using  a  too  coarse  investment  and  the  careless 
manner  of  applying  it. 

It  is  preferable  to  use  a  fine  investment  first,  one  which  is  easily  painted  over  the 
surface  of  the  pattern  and  later  invest  in  the  cup  with  a  coarser,  more  substantial 
material.  An  excellent  preparation  for  first  coating  the  pattern  is  equal  parts 
powdered  rouge  and  plaster,  while  there  seems  to  be  nothing  better  than  equal  parts 
of  extra  fine  powdered  silex  and  plaster  for  the  outer  investment.  If  these  invest- 
ments are  prepared  by  the  dentist,  he  should  be  careful  about  thoroughly  mixing  the 
ingredients,  otherwise  the  investment  will  crack  and  shrink.  It  should  be  passed 
through  a  fine  sieve  at  least  five  times. 

After  removing  the  wax  pattern  from  the  cavity  and  attaching  the  sprue  wire, 
examine  very  carefully,  and  if  there  is  any  collection  of  saliva  or  blood,  the  pattern 
should  be  thoroughly  cleaned,  first,  in  a  stream  of  water  from  a  water  syringe,  then 


PORCELAIN  AND  GOLD  INLAYS  191 

wiped  carefully  with  a  brush  or  pledget  of  cotton,  moistened  in  alcohol.  Attach  the 
sprue  wire  to  crucible  former  and  we  are  ready  to  invest. 

Mix  a  small  teaspoonful  of  the  red  investment  with  water  until  it  is  the  con- 
sistency of  thick  cream,  then  with  a  small  camel's  hair  brush  paint  the  surface  of  the 
pattern  carefully,  making  the  first  application  very  thin  and  be  particular  about  work- 
ing it  into  every  minute  angle.  Gradually  build  up  with  this  investment  until  there 
is  a  thickness  of  at  least  1-8  inch  over  the  entire  pattern.  This  investment  should 
extend  down  over  the  sprue  wire  and  crucible  former,  otherwise  there  might  be  a 
slight  crack  between  the  fine  and  the  coarse  investments,  which  would  fill  with 
gold  and  possibly  destroy  the  value  of  the  inlay. 

After  the  fine  investment  has  set,  nearly  fill  the  cup,  if  you  are  using  that  style  of 
receptacle,  with  the  coarser  investment  and  invest  the  pattern  and  sprue  and  with 
gentle  jarring  settle  to  place.  If  a  ring  is  being  used,  set  it  over  the  inlay  and  fill 
with  the  investment,  being  careful  to  work  into  every  minute  crevice  and  irregularity 
of  the  first  investment. 

After  the  investment  has  set,  the  ring  should  be  placed  over  a  slow  fire  to  dry. 
It  is  preferable  to  have  the  investment  heat  slowly,  as  there  is  less  danger  of  a  change. 
The  heat  should  be  gradually  increased  until  the  investment  is  a  dull  red  to  the 
center,  when  it  is  ready  for  casting. 

PREPARATION    OF    GOLD 

It  is  very  important  to  have  our  gold  for  casting  free  from  all  foreign  matter 
before  placing  it  in  the  crucible  to  be  cast.  If  we  have  been  particular  with  the 
treatment  of  the  wax  pattern  previous  to  this  time  and  it  is  a  perfect  counterpart 
of  our  cavity,  very  little  burnishing  of  the  margins  is  necessary.  Consequently  it 
is  possible  to  use  our  scrap  plate  rather  than  pure  gold.  If  we  have  been  reasonably 
careful  with  our  scrap,  kept  it  free  from  platinum  or  silver,  the  color  is  not  bad  for 
fillings  and  it  has  the  advantage  of  retaining  its  shape  better  than  pure  gold. 

If  scrap  is  used,  it  should  first  be  boiled  in  50%  nitric  acid  to  remove  any  base 
metals  that  may  be  present,  wash  and  place  upon  a  charcoal  block  and  melt.  While 
the  mass  is  in  a  molten  condition  it  should  be  sprinkled  with  Ammonium  Chloride 
(Sal  Ammoniac).  This  should  be  repeated  untilthe  gold  ripples  like  water.  This 
may  be  remelted  in  a  carbon  crucible  and  cast  into  ingots  for  use  or  used  as  it  is. 

If  we  are  melting  our  gold  in  a  crucible  formed  in  the  investment  very  little 
flux,  if  any,  should  be  used,  as  there  is  danger  of  its  closing  the  opening  into  the 
mold,  thus  preventing  a  perfect  cast,  if  the  gold  goes  down  at  all. 

The  importance  of  having  our  gold  in  perfect  condition  for  casting  must  not  be 
overlooked. 

It  is  hardly  necessary  to  mention  machines  for  casting,  as  there  are  so  many 
and  all  will  get  results  if  properly  handled.  Some  require  a  little  more  care  than 
others,  but  good  inlays  may  be  had  in  any,  from  a  tin  can  lined  with  wet  asbestos 
to  the  most  complicated  machines.  I  think,  however,  the  centrifugal  principle 
among  inexperienced  college  students,  will  give  the  most  uniform  results. 

After  the  inlay  is  cast  it  should  be  washed  thoroughly  to  remove  all  invesc- 
ment  attached,  then  placed  in  Hydrofluoric  Acid,  which  will  remove  any  fused  silex. 
The  sprue  should  then  be  carefully  cut  off  and  the  cavity  surface  examined  minutely 
for  any  small  bubbles  of  gold  that  may  be  attached.  If  the  red  investment  was 
painted  on  very  thin  at  first  there  will  bo  little  troul)!e  in  lliis  respect. 


192  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

If  there  is  any  difficulty  in  getting  the  inlay  seated  in  the  cavity,  an  excellent 
method  is  to  heat  the  inlay  slightly  and  apply  a  very  slight  layer  of  mercury  to  the 
surface;  this  will  unite  with  the  gold  and,  upon  evaporating  away  with  increased 
heat,  the  gold  will  be  left  with  a  frosted  surface.  If  the  inlay  is  now  placed  in  the 
cavity  any  point  that  may  rub  against  the  walls  will  become  burnished  and  can  be 
cut  away.  When  the  inlay  goes  to  place  perfectly,  the  surface  should  again  be 
etched  for  the  better  adhesion  of  the  cement. 

All  inaccessible  surfaces  of  the  inlay  should  be  trimmed  and  polished  before 
setting.  However,  if  it  is  possible  to  reach  the  margin  with  a  burnisher,  it  should  be 
left  slightly  flush  to  permit  a  thorough  burnishing  before  the  cement  sets,  after  which 
the  margins  should  be  finished  and  polished  the  same  as  for  a  gold  filling. 


AMALGAM  BASE  FOR  GOLD  INLAYS 

By  Steele  F.  Gilmore,  D.D.S.,  Indianapolis,  Ind. 

In  deep  lying  approximal  cavities  that  are  inaccessible  (such  as  are  distal  cavities 
in  molars  and  bicuspids)  rendering  the  adaptation  of  the  wax  model  and  its  gold 
replica  to  the  cervical  border  uncertain,  resulting  in  secondary  or  recurrent  decay  at 
this  point,  this  method  is  indicated. 

Technic:  After  the  preliminary  opening  of  the  cavity  in  a  gross  way,  apply 
the  Ivory  band  matrix,  and  with  it  in  place  excavate  the  cavity  floor  with  right  angle 
burs.  The  matrix  acting  as  a  guide  to  your  instruments  prevents  them  from  slipping 
into  the  soft  parts,  causing  unnecessary  pain  and  irreparable  damage  to  the  delicate 
tissues  occupying  the  interdental  space.  If  you  are  satisfied  with  the  preparation 
of  the  cavity  floor,  together  with  its  buccal  and  lingual  walls,  remove  the  matrix  and 
carefully  stone  the  margins.  Now  if  the  approximal  surface  of  the  neck  of  the  tooth 
is  irregular  (concave,  for  instance)  you  can,  with  pliers,  so  swage  and  manipulate  this 
soft  steel  as  to  adapt  it  accurately  to  the  surface  above  mentioned.  Properly  mixed 
amalgam,  in  very  small  pellets,  may  now  be  vigorously  burnished  in  and  built  up  as 
far  as  your  judgment  may  dictate.  Insert  temporary  stopping  until  the  next  sitting, 
when  complete  preparation  of  the  occlusal  surface  can  be  made.  Or  a  quick  setting 
amalgam  may  be  used  and  the  model  obtained  at  the  first  sitting. 

Advantage:  A  perfect  adaptation,  without  any  of  the  elements  of  guess  work 
in  this  dark  corner.  The  surface  alignment  of  your  filling  is  automatically  provided 
for  at  the  cervical  margin.  To  the  delight  of  the  patient,  approximal  ti'immers  and 
burnishers  are  not  needed.  You  have  re-inforced  the  weak  point  of  all  inlays. 
There  can  be  no  electrical  disturbance,  since  the  two  metals  are  insulated  by  the 
intervening  cement. 


SOME  PLACES  WHERE  THE  CASTING  PROCESS  HAS  BEEN 
FOUND  USEFUL 

By  E.  T.  Tinker,   D.D.S.,   Minneapolis,   Minn. 

In  the  following  article  it  will  be  my  endeavor  to  give  3011  a  lew  appliealions 
of  the  casting  process. 

The  first  of  which  will  be  a  method  of  casting  a  coping  for  a  Richmond  or 
Porcelain  crown,  where  it  is  necessary  to  reproduce  the  entire  enamel  margin,  as  in 
cases  of  split  roots,  roots  that  have  been  supporting  crowns  and  through  improper 
preparation  are  causing  gingivitis,  as  well  as  many  other  cases  that  may  come  under 
our  care. 

CASTING   A   COPING    FOR    RICHMOND    OR    PORCELAIN   CROWN 

In  brief,  the  procedure  is  as  follows: 

Before  removing  all  the  enamel  and  beveling  the  root,  take  the  measure  and  make 
band  of  22k. -30g.  gold  plate,  contouring  and  roughly  fitting  same  (Fig.  1).  Prepare 
the  root  as  in  Fig.  2;  place  the  band  in  position  and  force  softened  casting  wax  to 
place  (Fig.  3).     The  band  being  slightly  larger  than  the  root  acts  as  a  matrix,  forcing 


1 


S 


Figs.  1,  2,  3,  4  and  5 

the  wax  in  direct  contact;  the  free  margin  of  the  gum  determines  the  depth  to  which 
it  shall  go.  Trim  away  all  surplus  wax,  warm  an  iridio-platinum  pin  and  force 
through  wax  into  the  canal,  attach  the  sprue  and  remove  band,  wax  and  post  intact, 
mounting  same  on  crucible  former  (Fig.  4)  and  cast.  By  the  aid  of  stones  and  disks, 
dress  down  and  polish,  leaving  a  finished  co];ing  (Fig.  5),  which  is  very  strong  and 
one  to  which  the  gums  take  kindly. 

I  was  very  much  interested  in  reading  Doctor  Kabeli's  article  in  the  May 
number  of  Items  of  Interest,  from  the  fact  that  it  brought  out  the  same  difficulty 
which  some  of  my  friends  as  well  as  myself  have  been  ha\ing  with  the  shrinkage  of 
gold  when  cast. 


194 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


TIN    FOIL    TO   CONTROL    SHRINKAGE    IN   CASTING 

Through  the  courtesy  of  Doctor  H.  A.  Knight,  I  will  give  you  his  method  of 
using  tin  foil  to  control  the  shrinkage  in  casting  boxes  for  porcelain  bicuspids  and 
molars  when  used  as  dummies  for  bridge  work.  Take  a  common  pin  tooth,  molar  or 
bicuspid,  cut  off  the  pins  and  grind  it  as  shown  in  Figs.  6  and  7;  Fig.  6  showing  it 
from  the  occlusal  and  Fig.  7  from  the  gingival  point  of  view.  Take  a  sheet  of  casting 
wax  and  adapt  some  very  thin  tin  foil  over  one  side  of  it.  Warm  the  wax  and  press 
to  place,  having  the  tin  foil  next  to  the  ground  surface  of  the  tooth  and  carve  as  you 
wish  the  finished  piece.     Attach  the  sprue  in  some  convenient  place,  chill  and  using 


8 


Figs.  6,  7,  8  and  9 

sprue  as  a  handle,  remove  wax  and  foil  from  the  tooth,  chill  again  and  with  a  pair  of 
small  pliers  grasp  the  foil  by  some  small  projection  and  separate  from  the  wax  (Fig. 
8),  being  careful  not  to  distort  wax  form,  invest  and  cast.  The  space  gained  by  the 
foil  will  just  about  compensate  for  the  shrinkage  of  the  gold,  the  tooth  slipping  to 
place  without  further  grinding  (Fig.  9). 


Figs.  10.  11  and  12 


GINGIVAL   MARGIN    RESTORATION 

Another  place  where  difficulty  is  often  encountered  is  at  the  gingival  margins 
in  large  M.  O.  D.  inlays.  Doctor  F.  B.  Kremer,  of  this  city,  suggested  that  in  cases 
where  we  have  an  otherwise  perfect  inlay,  that  we  grind  away  a  part  of  the  defective 
margin  (Fig.  10),  placing  a  little  inlay  wax  and  forcing  inlay  home  over  it  (Fig.  11). 
Remove  inlay  and  wax  intact,  casting  anew,  which  gives  a  very  good  result  (Fig.  12). 
This  idea  has  been  carried  out  in  a  good  many  different  ways,  for  instance  where  a 


WHERE  THE  CASTING  PROCESS  HAS  BEEN  FOUND  USEFUL         195 

margin  of  a  cavity  containing  an  otherwise  good  inlay  has  become  fractured,  or 
where  a  root  has  become  affected  by  caries  under  a  well  made  Richmond,  the  de- 
fective parts  of  tooth  can  be  prepared,  wax  placed  over  them  and  the  old  work 
pressed  to  place,  removed  intact  and  cast,  producing  practically  a  new  piece  of  work. 
Numerous  other  conditions  will  present  themselves  to  which  this  idea  can  be  applied 
advantageously. 

CAST    C;OLD    CROWN 

For  contact,  contour,  occlusion  and  perfect  relation  to  the  root  and  gums,  the 
gold  crown  made  by  the  following  method  comes  as  near  the  ideal  for  posterior  teeth 
as  anything  I  have  as  yet  found.  Prepare  the  root  along  the  accepted  lines,  construct 
a  gold  band  of  22k. -30g.  plate  and  accurately  adjust  to  the  root  and  gingival,  paying 
no  attention  to  contour  as  that  will  be  taken  care  of  later.  Obtain  a  bite  of  occluding 
teeth  in  wax  and  an  impression  of  band  and  teeth  mesially  and  distally  in  plaster. 
Remove  band  and  place  it  in  impression.  Make  models  and  mount  on  an  anatomical 
articulator,  oil  all  plaster  adjacent  to  band,  place  warm  casting  wax  in  band  and  close 
the  articulator,  giving  it  a  lateral  motion  as  in  mastication,  so  as  to  produce  a  correct 
occlusion,  and  carve.  With  a  camel's  hair  brush  paint  melted  wax  on  exterior  of 
band  and  carve  contact  points  and  contour.  Remove  from  model,  invest  and  cast 
and  when  finished  it  will  be  found  as  near  anatomically  correct  as  any  which  have  so 
far  been  made,  and  its  one  great  advantage  lies  in  the  fact  that  by  not  contouring 
the  band,  we  do  not  take  the  risk  of  disturbing  its  relation  to  the  root,  the  perfection 
of  which  we  are  all  aware  is  the  cardinal  point  in  the  construction  of  any  crown,  the 
health  of  the  surrounding  tissues  and  the  life  of  the  operation  depending  almost 
wholly  upon  it. 


CAST  GOLD  SPLINTS  FOR  PYORRHEA 

By  Dr.  J.  G.  Lane,  Philadelphia,  Pa. 

Showing  more  particularly  a  method  of  uniting  the  two  plates  of  the  splint 
and  the  technique  of  making  up  the  uniting  medium. 

Fig.  1.  Finished  splint  in  position.  The  two  plates  fastened  tosrethcr  by  means 
or  iridio-platinum  screws. 


J  /' 


^^^ 


J.  G.   LANE,    D.  D.  S. 
OM   830    PERRY    BUILDING 

PHILADELPHIA 


Fig.  2.  Pattern  for  one  plate  of  splint,  showing  graphite  rods  in  position  to 
core  the  hole  for  the  screws.  In  order  to  get  the  proper  lineup  for  the  cores  they  are 
placed  in  wax  pattern  before  the  latter  is  removed  from  the  model. 

Fig.  3.  Iridio-platinum  blank  for  screw.  Surplus  material  for  head  obtained 
by  partly  fusing  the  end  of  the  wire. 

Fig.  4.  Heading  tool.  Made  by  drilling  a  hole  in  a  piece  of  steel  and  councer- 
boring  the  hole  to  any  sufficient  depth  with  a  round  bur.     This  must  be  tempered. 


Fig.  r>.  Sketch  showing  section  of  Heading  Tool.  (Xotc  shape  and  depth  of 
counter-bore.) 

Fig.  ().  Screw  blank  after  same  has  been  placed  in  the  Heading  Tool  and  the 
surplus  for  head  hammered  down  in  counter-bore. 

Fig.  7.  Finished  screw.  Shank  threaded,  surplus  material  on  head  removed 
with  a  file  and  slot  cut  with  ribbon  saw. 


CAMPBELL'S   COW-BELL   METHOD   OF  CASTING   PLATES 

By  Dayton  Dunbar  Campbell,  Kansas  City,  Mo. 

In  describing  this  simple  and  unique  method  of  casting  aluminum  plates,  we  will 
not  go  into  the  question  of  the  superiority  of  the  cast  metal  denture  over  one  made 
of  x'ulcanitc,  but  give  in  a  homely  way  the  procedure  in  detail: 

INVESTMENT    MATERIAL 

After  taking  your  impression,  coat  it  with  your  favorite  separating  fluid  and 
when  dry  rub  well  with  soapstone  and  pour  with  an  investment  compound  after  the 
formula  originated  by  Dr.  C.  C.  Allen,  which  consists  of  equal  parts  of  Portland 
cement  and  dental  plaster.  This  compound  is  in  keeping  with  the  simplicity  of  the 
casting  machine,  and  in  fact,  is  cheaper  than  plaster,  sets  very  fast  and  is  free  from 
shrinkage  and  expansion,  making  an  ideal  compound  in  bridge  work. 

It  is  hardly  necessary  to  say  that  the  plaster  and  cement  must  be  mixed  dry 
beforehand,  and  so  thoroughly  that  when  patted  down  with  a  spatula  no  particles 
of  plaster  are  distinctly  recognized.  To  obtain  the  best  results,  this  material  must 
be  worked  thicker  than  plaster. 

SEPARATION 

On  separating  the  impression  from  the  model,  if  the  former  when  poured  is 
jarred  down  well,  the  model  will  present  a  finished  surface.  The  part  of  the  model 
the  plate  is  to  cover  is  now  rubbed  well  with  soapstone.  This  gives  the  model  a 
metallic  luster  and  a  surface  very  desirable  to  cast  metal  against. 

WAX 
The  model  is  now  covered  with  a  new,  clean  piece  of  common  yellow  base-plate 
wax  and  care  taken  that  it  is  of  even  thickness  throughout,  and  that  it  has  not  buckled 
on  the  ridge  in  the  median  line.  The  wax  is  now  trimmed  as  you  wish  the  plate  to  be, 
and  care  taken  to  cut  it  low  where  the  depressor  muscles  have  action,  usually  in  the 
region  of  the  first  bicuspid.  The  outer  edge  of  the  wax  is  now  stuck  to  the  model  all 
the  way  around  with  a  dry,  sizzling-hot  spatula,  held  at  a  right  angle  with  the  wax. 
A  strip  of  wax  3-lG  of  an  inch  wide  is  now  cut  lengthwise  from  a  sheet  of  wax  and 
laid  down  flat  on  the  wax  model,  even  with  the  edge,  except  near  the  heel  of  the  plate, 
where  it  is  brought  over  to  the  lingual  surface.  The  wax  strip  is  brought  as  near 
the  top  or  bottom  of  the  ridge  on  the  palatal  or  lingual  surface  as  the  case  will  permit, 
the  idea  being  to  do  away  with  as  much  rubber  as  is  possible.  The  outer  sixteenth 
of  this  strip  is  now  made  a  part  of  the  wax  model  by  thrusting  a  dry,  hot  spatula 
through  the  strips  all  the  way  around  until  the  model  is  felt  beneath.  The  surface 
next  the  outer  border  of  the  strip  is  now  filled  in  with  wax  and  smoothed  up  with  a 
chip  l)lower  and  alcohol  lamp,  care  being  exercised  to  leave  the  inner  edge  of  the  strip 
sc|uare.  At  this  point  lower  the  temperature  of  the  wax,  which  has  become  soft  by 
working,  by  dipping  model  and  all  in  water  that  is  not  cold;  then,  with  a  dull  instru- 
ment, raise  the  inner  border  of  the  wax  strip  all  the  7vay  round,  as  is  shown  on  right 
side  of  Model  No.  1.  It  should  be  lifted  away  most  near  the  canine  eminence  and 
the  lingual  border  of  the  heel.  If  this  is  done  right,  it  affords  all  the  attachment 
necessary.   Sometimes  it  would  be  impracticable  to  use  the  strips  on  the  labial  border; 


198      •  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

it  can  be  done  away  with  altogether,  and  for  the  attachment  of  the  rubber,  loops  of 
German  silver  or  aluminum  can  be  set  in  place  on  the  wax  and  cast  successfully.  Of 
course,  there  is  no  union  of  the  metals,  but  they  are  held  in  place  mechanically  tight 
enough  to  serve  their  purpose. 

If  you  desire  to  cast  directly  on  the  teeth,  the  front  is  left  open  for  the  pink 
rubber,  and  a  space  of  one-half  to  one  millimeter  left  between  all  the  teeth.  This  is 
imperative,  because  the  contraction  of  the  alloy  or  metal  used  in  casting  the  teeth 
would  all  be  checked  or  broken  off. 

The  model  is  now  trimmed  even  with  the  heel  of  the  plate  and  a  little  roll  of  wax, 
about  the  size  of  a  slate  pencil  and  about  three  inches  long,  is  stuck  on  the  model 
with  a  hot  spatula,  even  with  and  joined  to  the  wax  plate.  Don't  lay  this  piece  of 
wax  over  on  the  wax,  as  it  will  not  facilitate  casting,  buf  will  be  difficult  to  remove 
in  the  cast. 

The  last  thing  to  do  before  you  invest  is  to  cut  the  model  all  over  to  get  rid  of 
the  "slazy"  surface  it  has  taken  on  from  handling,  rubbing  with  soapstone,  etc., 
so  it  will  unite,  so  to  speak,  with  the  investment,  and  put  it  in  a  bowl  of  cold  water. 
The  flask  is  a  No.  $  Hoosier  cowbell,  and  will  cost  you  seventy  cents. 

The  strap  at  the  top  of  the  bell  is  placed  in  a  heavy  vise  and  removed.  The 
rivet  that  holds  the  clapper  is  filed  off  some  and  driven  out  with  a  punch.  A  one- 
eighth  inch  hole  is  bored  a  half-inch  from  the  mouth  of  the  bell  at  its  extreme  width 
on  either  side,  to  afford  attachment  for  three  feet  of  bailing  wire,  and  you  now  have 
a  plate-casting  machine,  as  shown  in  the  cut. 

INVESTING 

To  invest:  Begin  mixing  your  home-made  investment  compound,  and  while  it 
is  thin,  remove  the  model  from  the  water  and  with  a  camel's  hair  brush  fill  in  the 
grooves  made  by  lifting  the  wax  strip;  then,  working  quickly,  mix  the  investment 
thick  and  pour  it  in  the  cow-bell  (it  should  be  not  quite  two-thirds  full),  now  put  in 
the  model;  then,  by  holding  the  cowbell  between  the  thumb  and  three  fingers  of 
either  hand,  the  index  fingers  are  left  free  to  push  the  model  down;  it  should  be 
jarred  and  pushed  down  until  the  model  is  about  an  inch  below  the  surface,  or,  say 
until  the  fingers  are  in  the  investment  to  the  first  joint.  Now  remove  the  fingers, 
and  by  pressing  on  the  wax  pencil  the  model  is  kept  in  place  while  the  jarring  is 
continued  until  the  surface  of  the  investment  is  even. 

The  surface  now  presents  a  semi-liquid  appearance  which  is  immediately 
sprinkled  with  the  dry  investment  to  hasten  the  setting.  In  a  very  few  minutes  the 
top  of  the  investment  is  scraped  with  a  large  vulcanite  scraper  (no  attention  is  paid 
to  the  wax  pencil,  it  being  cut  or  twisted  off  and  scraped  down  with  the  investment); 
until  it  is  firm  and  solid.  Then  the  investment,  from  an  inch  to  an  inch  and  one-half 
on  all  sides  of  the  wax  is  lowered  about  one-half  inch  and  the  whole  top  washed  out 
to  get  rid  of  any  small  particles  that  might  fall  into  the  investment  and  cause  a  hole 
in  the  plate. 

The  bell  is  now  placed  on  a  slow  fire  and  the  wax  burned  out. 

This  idea  of  the  disappearing  model,  of  course,  belongs  to  Dr.  Taggart,  and  it  is 
to  him  all  credit  should  be  given  should  this  article  prove  beneficial  to  you. 

The  burning  of  the  wax  usually  takes  an  hour  or  more.  When  the  bell  can  be 
removed  from  the  fire  and  there  is  absolutely  no  smoke  issuing  from  it,  you  are  ready 
to  cast.  The  flask  does  not  have  to  be  ver}'  hot,  and  for  this  reason  a  very  good 
cast  can  be  made  over'  a  common  plaster-paris  model.     If  you  are  going  to  cast 


CAMPBELL'S  COW-BELL  METHOD  OF  CASTING  PLATES         199 

directly  on  the  teeth,  the  method  of  investing  and  removing  the  wax  is  also  a  little 
different.  The  teeth  are  painted  with  whiting  to  prevent  any  excess  of  the  metal 
adhering  to  the  porcelain,  a  phenomenon  that  occurs  that  to  me  is  very  striking. 
An  attempt  to  remove  a  film  of  the  aluminum  that  may  have  run  over  one  of  the  teeth 
without  whiting  means  to  remove  just  so  much  of  the  porcelain. 

Place  the  flask  on  its  side  in  a  clean  vessel  and  fill  with  cold  water  until  it  is 
covered  two  or  three  inches,  set  on  a  slow  fire  and  bring  to  a  boil  until  the  wax  is  all 
out.  Place  on  fire  as  before  and  heat  slowly,  but  in  this  case,  before  you  cast,  the 
case  must  be  heated  pretty  hot  to  bring  the  temperature  of  porcelain  up  to  something 
near  the  temperature  of  the  molten  metal. 

To  cast,  the  cowbell  is  laid  on  one  side  with  the  mouth  elevated  an  inch  or  so. 
An  ingot  of  pure  aluminum,  or  Aerdentalloy,  is  then  laid  in  the  mouth  of  the  bell 
and  melted  with  a  common  gasoline  blow-pipe.  As  the  metal  melts  the  bell  is  raised 
and  it  runs  over  the  hole  left  by  the  wax.  This  is  done  for  two  reasons — first,  to 
keep  out  any  small  particles  that  might  fall  into  the  mold,  and  to  give  you  better 
access  with  the  blow-pipe  until  the  metal  is  thoroughly  melted  "and  a  little  bit 
more,"  then,  without  hurrying,  but  rather  on  the  pokey  order,  lay  aside  the  blow- 
pipe, take  hold  of  the  bale,  already  cold,  and  get  where  you  will  have  plenty  of  room; 
swing  the  bell  back  and  forth  like  a  pendulum  once  or  twice  and  then  over  your  head, 
like  you  would  a  small  bucket  of  water.  The  plate  is  cast,  of  course,  the  first  round, 
but  the  swinging  should  be  kept  up  half  a  minute,  so  that  crystallization  may  take 
place  under  pressure.  All  casts  made  in  this  manner  are  better  on  account  of  their 
closer  molecular  construction. 

The  flask  is  now  allowed  to  cool  and  the  investment  and  plate  shaken  out; 
the  excess  cut  oflf  with  a  hack-saw  and  the  plate  finished. 

The  impression  can  be  waxed  up  or  the  model  scraped  down  at  this  point,  but 
it  is  purely  guess  work  and  unscientific.  As  a  last  resort,  when  the  plate  is  cast  and 
still  needs  to  be  raised  at  this  point,  a  plaster  model  of  the  plate  is  poured,  and  when 
very  hard,  removed  and  scraped  down  as  far  as  you  want  the  plate.  The  plate 
is  then  placed  back  on  the  model  and  with  a  ball  hammer  beaten  down  to  place. 


WILSON'S  CAST  ALUMINUM  PLATES 

By  George  H.   Wilson,  D.D.S..  Cleveland,  Ohio. 

1.     Cast  of  silica  sand,  wash  silica  and  plaster  of  Paris,  equal  parts  by  measure. 
Base-plate  of  paraffin  built  up  with  pure  yellow  beeswax,  showing  stages  of  con- 


Waxed  impression,  showing  method  of  waxing 


Finished  casting 


Casting  as  it  came  from  investment 


WILSON'S  CAST  ALUMINUM  PLATES  201 


Showiiu^  uhiniimiin  cast  to  teeth  on  palatine  surface 


202  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

struction;  also  the  sprue  formers.     The  pouring  sprue  must  not  exceed  3-16  of  an 
inch. 

2.  Casting  as  made  in  the  BiUmej^er  bucket. 

3.  Finished  pure  aluminum  base-plate. 

4.  Complete  denture  mounted  on  Snow  antagonizer.  The  upper  is  cast  direct 
to  the  tooth.  This  is  not  practicable  with  platinum  pin  teeth,  as  aluminum  is  a 
solvent  for  platinum.  Attachment  of  the  teeth  with  vulcanite  is  the  practicable 
and  desirable  method  as  exemplified  in  the  lower  denture. 


SOME  PHASES  OF  THE  CASTING  PROCESS 

By  C.  S.   Van  Horn,  D.D.S.,    Bloomsburg,   Pa. 

To  test  a  pattern  wax  hold  a  piece  in  the  mouth  until  it  assumes  body  temper- 
ature, when,  if  it  becomes  plastic,  susceptible  to  change  on  moderate  pressure  either 
by  the  teeth  or  fingers,  it  is  not  suitable  for  the  purpose  for  which  it  was  designed. 
There  is  a  long  train  of  maladies  attending  the  use  of  a  plastic  wax  that  may  be 
largely  or  entirely  eliminated  by  the  use  of  a  non-plastic  wax. 

Assuming  the  cavity  to  be  approximo-occlusal,  involving  all  or  part  of  one  or 
more  cusps,  either  of  bicuspids  or  molars,  the  wax,  which  has  previously  been  softened 
in  water  at  183  degrees  F.,  is  quickly  thrust  into  the  cavity  and  molded  quickly  to 
place,  and  the  patient  directed  to  bring  the  teeth  into  normal  occlusion,  when  with 
the  fingers  and  proper  instruments  the  buccal  surplus  is  pressed  into  contact  with  the 
buccal  wall  of  the  cavity,  the  instrument  being  pressed  into  the  interproximal  space, 
thus  forcing  the  wax  into  contact  with  the  cervical  margin  of  the  cavity.  As  a 
generous  surplus  of  wax  has  been  used  we  have  a  rather  uninviting  appearing  mass, 
which  is  soon  reduced  by  rough  carving  to  something  like  normality.  In  carving  it 
is  of  the  utmost  importance  that  the  pattern  remain  stationary  in  the  cavit3^  i.  e., 
without  moving  and  rubbing  against  the  cavity  wails;  the  best  way  to  prevent  this 
is  to  carve  the  occlusal  surface  before  disturbing  the  contact  of  the  pattern  with  the 
adjacent  tooth.  The  support  given  to  the  pattern  by  the  adjacent  tooth,  together 
with  properly  directed  force  in  carving,  enables  us  to  make  the  most  extensive  restor- 
ation with  seldom  an  appreciable  movement  of  the  pattern.  After  the  occlusal 
surface  has  been  carved,  our  attention  is  directed  to  the  lingual  margins,  then  to  the 
buccal  margins,  and  lastly  to  the  cervical  margins,  all  these  margins  being  finished 
flush  with  the  square  tooth-margins  for  reasons  previously  described. 

We  now  have  a  pattern — not  an  impression — carved  to  form,  except  that  it  has 
a  contact  surface — not  point — with  the  adjacent  tooth,  and  is  unpolished.  The 
polishing  should  be  done  in  the  same  order  as  the  carving;  First,  the  occlusal  surface 
is  gone  over,  touched  where  necessary  with  the  carving  instruments  to  bring  out  any 
artistic  lines,  and  highly  polished;  then  the  lingual  and  buccal  margins.  Then  with  a 
pellet  of  cotton  wet  with  cold  water  and  held  against  the  occlusal  surface  to  prevent 
any  movement  of  the  pattern,  a  hot,  very  thin  flat  instrument  is  passed  between  the 
adjacent  tooth  and  the  pattern,  and  the  abnormally  large  contact  surface  converged 
into  a  normal  contact  point,  and  polished  with  a  wisp  of  cotton,  the  teeth  having 
been  previously  separated,  as  they  always  should  be,  to  admit  of  a  subsequent 
normal  contact  being  formed. 

If  all  the  steps  have  been  followed  with  precision  and  a  high  regard  for  artistic 
attainment,  we  have  a  beautiful  restoration  of  the  lost  part  in  wax. 


SOME  PHASES  OF  THE  CASTING  PROCESS  203 

To  extricate  the  pattern  an  explorer  is  usually  employed,  though  any  of  the 
well-known  methods  may  be  used,  being  especially  careful  to  prevent  the  slightest 
marginal  distortion.  Here  again  it  is  of  advantage  to  have  square  margins  where 
sheltered,  for  it  is  manifestly  easier  to  remove  without  distortion  a  pattern  with 
square,  well-defined  margins  than  it  is  to  remove  one  with  feather-edges.  The 
pattern  is  then  attached  to  the  sprue  and  examined  under  a  magnifying  glass  co  as- 
certain its  perfectness,  and  if  it  is  found  to  be  flawless  in  iis  marginal  impressions 
any  carving  which  may  be  deemed  essential  may  be  done  on  the  cavity  side — and  I 
might  say  right  here  that  it  is  seldom  that  the  cavity  side  of  the  pattern  should  not 
be  carved,  believing  that  by  so  doing  we  increase  the  efficacy  of  the  finished  product. 
This  carving  on  the  cavity  bide  may  be  easily  and  expeditiously  done  with  a  light, 
sharp  lancet  or  a  bur  in  the  engine,  or  a  combination  of  both.  The  finishing  touches 
being  completed,  the  pattern  is  ready  for  investing. 

INVESTING 

It  is  just  as  essential  that  the  investing  be  properly  done  as  any  other  part  of  the 
procedure.  I  have  noted  that  some  use  scales,  others  measures  to  apportion  the 
investment  and  water.  I  am  not  prepared  to  comment  on  this  procedure,  except  to 
say  that  at  present  I  use  neither.  The  investment  should  be  mixed  just  as  thick 
as  it  can  be  and  yet  admit  of  the  pattern  being  properly  invested,  and  as  it  requires 
more  time  to  coat  a  complex  than  it  does  a  simple  pattern,  it  is  obvious  that  the 
investment  should  be  mixed  accordingly.  Then,  too,  some  are  more  dextrous  than 
others,  being  capable  of  working  with  a  much  stiffer  mix.  Personal  equation  being 
such  a  potent  factor  in  all  our  work  makes  it  next  to  impossible  to  formulate  laws 
for  operative  procedures  in  the  field  of  dentistry. 

Ten  to  fifteen  minutes  after  investing  the  pattern  the  investment  is,  or  should 
be,  sufficiently  hard  to  admit  of  the  sprue  being  removed,  which  should  be  done  by 
heating  the  sprue  to  a  full  red  heat  for  several  minutes  and  twisting  it  out  with 
pliers,  thus  preventing  any  distortion  of  the  mold.  Remember  that  we  are  dealing 
with  the  investment  while  in  a  semi-set  condition,  and  great  care  is  essential  to 
success. 

The  flask  is  immediately  placed  over  a  very  low  flame,  a  flame  of  just  sufficient 
heat  to  drive  out  the  moisture  without  creating  steam,  and  as  soon  as  the  investment 
is  dry  the  flame  is  increased  and  the  wax  burned  out.  Formerly,  the  investment  was 
allowed  to  dry  over  night,  but  1  believe  this  to  be  at  variance  with  scientific  findings 
relative  to  the  setting  of  plaster  of  paris,  one  of  the  ingredients  in  the  investment. 
Be  this  as  it  may,  I  obtain  better  results  by  placing  the  "green"  investment  over  a 
low  flame  ten  to  fifteen  minutes  after  flasking — the  castings  are  just  as  smooth,  just 
as  sharp,  and  without  "feathers." 

CASTING 

It  is  obviously  impossible  to  go  into  extended  detail  of  casting  without  consider- 
ing the  numerous  devices  that  have  been  placed  upon  the  market  for  the  purpose, 
and  this  in  itself  would  require  a  paper  of  considerable  length.  My  advice,  therefore, 
is  after  mastering  cavity  preparation  and  formation,  to  master  the  complete  tech- 
ni(|ue,  and  then  it  is  time  to  master  the  device  with  which  you  expect  to  do  the  casting. 
I  fear  that  a  great  man\  ha\e  fallen  and  that  more  will  fall  by  the  wayside  by  be- 
ginning at  the  reverse  end.  That  which  go(;s  to  make  up  the  entire  casting  problem 
is  by  no  means  easy  of  solution,  nor  suited  to  perfunctory  methods  or  desultory 
application. 


204  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

At  present  our  work  in  this  field  is  largely  cni|)irical;  wc  lia\e  not  practiced 
castina;  sufficiently  long  to  have  established  it  on  a  scientific  basis,  consequently  we 
are  too  many  times  between  the  devil  and  the  azure  brine  to  know  the  how  and  the 
why.  Some  day  the  clouds  will  clear,  and  we  shall  broaden  our  horizon  and  place 
casting  on  a  scientific  basis.  Then  we  shall  have  what  we  have  not  now,  a  perfect 
casting  machine,  a  machine  which  will  be  automatic  in  its  action,  indicating  the  exact 
pressure  on  the  gold  in  the  mold  and  at  the  same  time  the  temperature  of  the  metal, 
just  as  our  pyrometer  furnaces  indicate  the  temperature  of  the  porcelain.  This 
together  with  a  perfect  pattern  wax  and  a  perfect  investment  rhaterial  will  have  a 
powerful  influence  in  eliminating  stumbling  blocks  in  the  paths  of  those  not  especially 
adapted  or  reasonably  versatile. 

The  two  most  important  considerations,  with  the  present  machines  arc  to  de- 
termine the  requisite  pressure  and  the  proper  state  of  fluidity  of  the  gold.  Too 
much  pressure  will  expand  and  crack  the  investment,  causing  an  imperfect  casting, 
and  if  the  gold  is  not  sufficient!}'  fluid  a  sharp  casting  is  not  to  be  anticipated. 

No  machine  of  which  1  have  any  knowledge  will  give  an  exact,  sustained,  de- 
terminable pressure  on  the  gold  in  the  mold,  arid  with  the  machines  of  the  "plunger" 
type  it  is  risky,  if  you  have  a  regard  for  veracity,  to  hazard  a  guess  on  the  pressure. 
Therefore,  no  difference  what  device  you  use,  experiment  until  you  have  mastered  it, 
and  by  that  time  you  will  have  discovered  that  the  more  fluid  the  gold  is  at  the  time 
when  force  is  applied,  the  shai-per  the  casting  will  be. 

One  way  of  determining  the  proper  state  of  fluidity  of  the  gold  is  this:  First 
the  gold  assumes  a  globule,  then  the  "bull's-eye "  appears,  and  finally  we  get  what  may 
be  termed  the  sun-glow.  When  this  stage  is  reached,  if  you  are  watching  the  gold 
very  closely,  3'ou  will  notice  a  very  slight  spreading  and  flattening  of  the  globule; 
this  is  the  time  to  put  on  the  pressure,  and  if  it  is  done  properly,  and  if  24k.  gold  in 
very  generous  quantity — a  quantity  admitting  at  least  5  dwt.  surplus — is  the  metal, 
you  may  be  reasonably  certain  of  success,  though  on  rare  occasions  failure  will  stare 
you  in  the  face.  But,  since  it  is  in  degree  by  our  failures  that  we  advance,  they  are 
not  always  to  be  despised  but  rather  viewed  as  stimulants  to  subsequent  success 
through  fathoming  the  cause.  "If  at  first  you  don't  succeed."  ascertain  the  cause, 
for  the  effect  will  follow  in  natural  sequence. — Cosmos. 


THE  WORKING  MODEL  FOR  INLAY  PRACTICE 

By  H.  W.  Arthur,  D.D.S.,  Sc.D.,  Pittsburg,  Pa. 

1 1  is  not  the  purpose  of  this  paper  to  advocate  the  use  of  the  working  model  to  the 
exclusion  of  the  direct  rqethod  of  practice  in  making  inlays. 

The  working  model  method,  aside  from  the  fact  that  it  is  not  so  expeditious,  has 
otherwise  all  the  advantages,  as  well  as  supplying  the  means  of  overcoming  difficulties 
attending  the  direct  method  of  practice.  In  any  and  all  cases,  an  accurate  adap- 
tation to  the  cavity  with  contact  and  occlusion,  in  bicuspids  and  molars,  as  well  as  the 
more  simple  cases,  can  be  assured  by  the  working  model  method.  The  working 
model,  while  specially  to  be  preferred,  for  the  production  of  porcelain  inlays,  meets 
all  the  requirements  for  gold  inlays.  With  the  working  model  as  it  should  be,  that 
is,  an  accurate  impression  of  the  cavity,  the  appro.ximating  tooth  and  the  correct 
occlusion,  the  operator,  in  this  class  of  cavities,  has  control  of  conditions  and  the 
manipulative  procedure  in  a  way  that  he  cannot  have  by  the  direct  method. 

Having  the  porcelain  inlay  specially  in  mind,  the  following  advantages  may  be 
claimed  for  the  working  model: 

The  cavity  can  be  approached  conveniently  from  all  directions,  so  that  the 
platinum  matrix  can  be  more  readily  adapted. 

The  porcelain  material  can  be  applied  with  the  platinum  matrix  on  the  model, 
thus  avoiding  the  liability  to  change  of  form  to  which  the  matrix  is  subject  when 
held  in  pliers. 

Proximal  contact  and  accuracy  of  occlusion  can  be  gauged  on  bicuspids  and 
molars,  and  more  readily  attained  with  the  anterior  teeth. 

Several  inlays  (there  need  be  no  limit  to  the  number)  of  different  shades  may  be 
made  with  but  little  more  expenditiux  of  time  than  for  one,  thereby  giving  a  choice 
of  the  one  best  suited  to  the  case. 

It  supplies  the  means,  in  case  of  an  accident,  of  repeating  the  operation  without 
annoyance  to  the  patient. 

Nicety  of  detail  can  be  worked  out  at  leisure. 

The  model,  properly  registered,  with  shade  record,  may  prove  convenient  for 
future  use.  Aside,  we  might  add,  that  the  temptation  to  insert  a  "good  enough" 
inlay  cannot  be  so  readily  excused. 

The  above  will  apply  equally  to  the  gold  inlay,  where  the  procedure  is  in  common. 

To  insure  the  best  results,  the  working  model  must  be  an  exact  reproduction  of 
cavity  and  surroundings,  as  found  in  the  mouth.  This  necessitates  that,  not  only 
should  the  impression  be  accurate,  but  that  there  should  be  no  change  of  bulk  of  form. 
Experience  has  demonstrated  that  modeling  composition  and  copper  amalgam 
supply  the  materials  that  meet  these  requirements.  Where  there  is  direct  access  to 
a  cavity,  a  good  impression  can  be  taken  by  the  simple  method  of  shaping  the  modeling 
composition  to  a  point  and  then  softening  the  point.  This,  with  the  harder  composi- 
tion to  give  resistance,  can  be  forced  to  all  parts  of  the  ca^•it^•  and  cavo-surface  angle. 


20(5 


PRACTICAL    MANUAL    OF    DENTAL    CASTING 


In  most  cases,  however,  a  suitable  ca\ity  tray  is  necessary  to  give  resistance  to 
force  the  impression  material  to  the  distant  parts  of  the  cavity  and  cavo-surface 
angle,  as  at  the  cer\ical  margins  of  proximal  cavities  and  under  the  gingiva-labial 
surfaces. 

To  meet  these  requirements  your  essayist  has  contrived  a  number  of  cavity 
trays,  described  as  follows: 

No.  1.  Designed  for  taking  impressions  under  the  lahio-gingival  margins  of 
the  anterior  teeth. 

Xos.  2  and  3.  Designed  for  taking  impressions  (rights  and  lefts)  of  the  prox- 
imal cavities,  mesial  and  distal,  of  the  anterior  teeth. 

Nos.  4  and  5.  Designed  for  taking  impressions  of  mcsio-occlusal  and  disto- 
occlusal  cavities  of  bicuspids  and  molars. 


No.  6.  Designed  for  taking  impressions  where  the  lingual  or  buccal  portion 
of  a  tooth  is  wanting. 

No.  7.     Designed  for  taking  impressions  of  labial,  buccal  or  occlusal  cavities. 

No.  8.  Designed  for  taking  impressions  of  disto-occlusal  cavities  of  third 
molars,  including  the  occlusion. 

A-  more  recent  device  has,  in  a  measure,  taken  the  place  of  Nos.  4  and  5.  It  is 
designed  not  only  to  take  an  impression  of  the  cavity,  but  includes  proximal  contact 
and  occlusion.  So  that,  mounted  on  the  articulator,  we  have  all  the  conditions  of 
the  mouth. 

The  device  is  simple,  designed  to  confine  the  impression  material;  can  be  made 
in  a  few  minutes.  The  same  appliance  has  been  used  by  your  essayist  as  a  matrix 
in  the  operation  of  filling  for  years.  It  co.nsists  of  a  thin  piece  of  sheet  metal,  shaped  to 
pass  above  the  cervical  margin  and  around  the  embrasures  of  the  tooth,  with  a  lip 
turned  down  to  rest  on  the  ridge  of  the  proximating  tooth.  The  appliance,  when 
in  place  on  the  proximating  surfaces  of  bicuspids  or  molars,  as  the  case  may  be, 


THE   WORKING  MODEL  FOR  I  NLA  Y  PRA  CTICE  207 

should  be  wedged  lightly  at  the  cervical  portion  with  cotton,  where  there  should  be  a 
slight  yielding,  so  that  the  impression  material  may  pass  over  the  margin  of  this 
portion  of  the  cavity. 

The  lip  resting  on  the  ridge  of  the  proximate  tooth  prevents  the  forcing  of  the 
appliance  onto  the  gum  when  taking  the  bite.  The  parts  of  the  appliance  passing 
around  the  embrasures  should  be  free  and  yet  not  enough  so  to  allow  the  impression 
material  to  pass  around  the  embrasures  to  the  extent  that  it  will  interfere  with  the 
withdrawal  of  the  impression. 

Sufficient  impression  compound  should  be  used  to  fill  the  cavity  and  cover  the 
occlusal  surfaces  of  the  adjacent  teeth.  The  patient  should  be  instructed  to  bite 
and  give  lateral  motion.  With  the  impression  in  hand,  copper  amalgam  is  prepared 
for  inserting  in  the  usual  way.  It  should  be  inserted  with  care,  pressed  well  onto  the 
thin  margins,  ox'cr  the  impression  of  the  ca\'ity  and  embrasures,  and  well  onto  the 
occluding  surface  of  the  tooth.  It  is  better  to  wait  until  the  amalgam  has  hardened 
before  completing  the  mounting  on  the  articulator. 

On  the  articulator  the  slight  obstruction  to  exact  occlusion,  caused  by  the  lip 
of  the  matrix,  is  corrected  in  the  absence  of  the  obstructing  lip. 

The  thickness  of  the  matrix  doesnot  interfere  with  securing  the  correct  proximal 
contact.  The  working  model  should  supply  all  the  conditions  of  the  mouth;  it  has, 
in  addition,  all  the  aforesaid  advantages  for  manipulations. 

The  appliances  we  have  described  are  so  readily  made,  and  the  taking  of  an  im- 
pression so  simple,  that  it  is  well  to  have  it  at  hand,  even  though  it  ma^'  only  be  for 
contingencies. 

Where  the  occlusion  and  contour  can  be  allowed,  as  in  the  anterior  teeth  or  on 
exposed  surfaces,  the  copper  amalgam  counter  of  the  impression  of  a  cavity  can  be 
mounted  in  plaster  in  a  suitable  receptacle,  thus  supplying  a  convenient  means  for 
forming  the  platinum  matrix  by  the  use  of  the  water  bag,  under  screw  pressure,  and 
for  correcting  the  shape  of  the  matrix,  if  need  be,  after  the  first  fusing  of  the  bod^-  in 
the  matrix. 

The  convenience  of  the  working  model  for  making  gold  inlays  is  too  ob\'ious  to 
enlarge  upon  it. 

Having  as  an  object  the  insuring  of  the  best  results,  as  a  means  to  that  end,  the 
working  model  has  a  place  not  only  in  inlay,  but  in  other  lines  of  practice. 

ABSTRACT  OF  DISCUSSION 

Dr.  Frank  L.  Wright,  Wheeling:  I  should  like  very  much  to  have  seen  a  copy  of  Dr.  .\rthur's 
paper.  I  have  never  used  copper  amalgam.  I  have  used  Dr.  Weston  A.  Price's  method  of  artificial 
stone,  which  is  perhaps  not  as  good,  but  I  have  had  some  very  good  results,  especially  in  proximal 
cavities  between  bicuspids  and  molars.  I  have  made  four  fillings  at  one  time,  using  artificial  stone; 
separating  a  little  to  get  the  contact  point,  and  have  had  results  in  fillings  dropping  right  into  place 
with  a  beautiful  contact  point.  The  advantage  of  any  model  is  the  almost  complete  finishing  of  your 
filling  before  putting  it  in  the  mouth.  You  can  polish  the  filling  on  the  artificial  stone  down  to  a  very 
fine  edge,  with  little  extra  work  necessary  after  cementing  your  filling.  The  only  method  I  am  familiar 
with  is  the  Dr.  Price  method.  He  has  different  little  impression  cups  for  taking  impressions.  He  uses 
a  wax,  and  the  artificial  stone  is  mixed  up  and  put  in  the  wax  after  it  hardens,  and  the  stone  does  not 
harden  until  after  heat  is  applied,  and  you  can  make  a  good  model  in  that  way.  Your  casting  wax 
is  then  molded  right  into  your  cavity,  contouring  it  the  same  as  Dr.  Arthur  has  told  us  about;  and  you 
can  get  perfect  occlusion.  Finish  your  filling,  and  if  you  have  two  or  three  proximal  cavities  using  his 
articulator,  breaking  your  model  apart.  It  is  nicely  adjusted  so  it  can  be  opened  for  contouring, 
graded  down  to  the  milometer;  spread  your  teeth  just  a  little  and  your  fillings  will  go  in  in  verj-  nice 
shape. 

Dr.  L.  G.  Beerbower,  Terra  Alta:     I  am  sure  we  have  all  appreciated  this  paper  very  much  and 


208  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

will  yain  many  splendid  points  from  it,  but  I  have  not  used  the  method  enough,  have  not  endeavored 
to  put  it  into  practice,  to  discuss  it.     I  know  it  is  a  good  method  from  a  common  sense  standpoint. 

Dr.  Arthur  (closing) :  I  have  endeavored  to  put  it  into  as  few  words  as  possible  and  make  it  as 
plain  as  possible.  I  claim  considerable  originality  in  what  I  have  produced  there,  and  I  am  satisfied 
when  you  see  it  in  clinic  you  will  see  that  it  is  a  valuable  means  in  producing  results.  That  is  what  we 
are  after. 

As  to  Dr.  Price's  method,  I  know  of  it;  have  practitioners  nearby  who  follow  it  up,  but  think  my 
method  is  simpler  than  Dr.  Price's  and  have  something  in  reserve.  In  Dr.  Price's  you  break  up  j'our 
model,  but  I  have  had  the  impression  that  in  breaking  that  up  you  are  likely  to  injure  your  filling. 
I  regard  it  as  a  good  method;  I  wouldn't  place  this  method  in  contrast  with  it  at  all;  I  am  .satisfied  that 
it  is  good  and  have  been  prompted  to  take  it  up,  but  have  not  just  done  so,  probably  because  of  my 
own  scheme. 


CONDUCTIVITY  OF  CAST  INLAYS 

By  S.   H.   Guilford,  D.  D.  S.  Philadelphia 

The  clanger  of  pulp  irritation  and  often  the  devitalization  from  placing  a  metal 
filling  in  contact  with  a  thin  layer  of  dentin  overlying  the  pulp  has  long  been  recognized 
and,  in  a  measure,  guarded  against  by  interposing  some  less  conductive  substance 
between  the  two. 

For  this  purpose  different  materials  have  been  used,  such  as  a  coating  of  varnish, 
a  layer  of  paper  or  asbestos  with  some  adhesive  and  non-irritating  medium  to  hold 
it  in  place,  and  either  alone  or  in  connection  with  any  of  the  foregoing,  a  layer  of 
one  of  the  cements. 

These  have  answered  their  purpose  remarkably  well  in  connection  with  foil 
fillings  but  only  the  last  one  has  been  found  really  available  when  cast  inlays  are  used. 

If  the  employment  of  an  intermediary  is  deemed  essential  under  a  foil  filling  in 
large  or  deep  cavities,  an  even  thicker  layer  of  non-conductive  material  is  necessary 
under  an  inlay  to  insure  subsequent  comfort  and  guard  against  pulp    devitalization. 

However  dense  a  foil  filling  may  be  it  is  never  so  dense  as  an  inlay.  The  former 
contains  a  portion  of  air  between  its  particles  and  air  is  one  of  the  best  non-conductors. 
In  the  latter  the  molecules  are  more  closely  in  contact  and  thermal  changes  are  in 
consequence  more  rapidly  transmitted. 

In  this  fact  lies  one  of  the  chief  dangers  in  the  emplo^'ment  of  the  cast  inlay. 
Another  fact  worthy  of  consideration  is  that  a  gold  filling  may  be  removed  piece- 
meal if  for  anj'  cause  the  tooth  should  be  sensitive  to  thermal  changes  after  being 
filled.  A  cast  inlaA^  could  not  thus  be  removed  and  would  have  to  be  pried  out 
with  wall  fracture  as  an  almost  certain  result. 

We  therefore  feel  that  the  necessity  for  providing  against  thermal  shock  under 
cast  inlays  should  be  strongly  emphasized. 

It  has  been  a  common  practice,  in  deep  cavities,  to  partially  fill  them  with  cement 
and  then  give  to  this  material  and  the  adjacent  walls  the  shape  necessary  for  the 
placing  and  removal  of  the  wax  inlay  form.  This  is  a  good  practice  and  in  many 
cases  has  to  be  resorted  to,  but  it  takes  time,  and  delay's  the  completion  of  the 
operation. 

A  better  plan,  in  cases  where  caries  has  not  made  too  extensive  inroads,  is  to 
remove  only  the  softer  portions  of  decay  and  prepare  the  cavity  so  that  the  wax 
form  will  draw,  at  the  same  time  shaping  all  margins  in  the  most  careful  manner 
just  as  we  wish  them  to  remain. 

After  the  inlay  is  constructed  and  ready  to  insert  the  inner  portion  of  the  cavity 
is  further  excavated  and  prepared  in  the  usual  manner.     The  removal  of  this  last 


CONDUCTIVnV  OF  CAST  INLA  VS  2Un 

portion  of  decalcified  material  forms  a  space  for  the  cement  to  occupy  when  the  inlay 
is  set.  But  this  is  usually  not  enough.  The  wax  form  after  its  removal  from  the 
cavity  with  the  sprue-wire  firmly  imbedded  in  it  should  be  reduced  in  size  on  its 
cavity  side  so  as  to  provide  greater  space  for  the  non-conducting  cement. 

This  is  an  exceedingly  delicate  operation  owing  to  the  danger  of  distorting  the 
form  and  rendering  it  useless.  To  trim  it  with  a  cold  spatula  or  bistoury  would 
necessitate  the  application  of  too  much  force.  A  heated  spatula  would  be  liable  to 
melt  too  much  of  the  wax  and  cause  it  to  flow  and  ruin  the  form.  Heat,  however, 
seems  to  be  the  most  available  medium  for  the  purpose  if  some  means  be  provided 
for  carrying  away  the  wax  as  fast  as  it  is  melted.  For  this  purpose  a  coujilc  of  de^'ices 
lia\c  Ix'en  placed  on  the  market  consisling  of  a  liandlr  with  a  bull)  or  receptacle 
near  its  (juter  end  and  a  metal  or  glass  capillary  tube  leading  from  it.  TIu'  liandle  is 
hollow  and  connected  with  an  exhaust  pump  of  some  form. 

When  the  bulb  is  heated  the  free  end  of  the  small  tube  is  applied  to  the  portion 
of  the  wax  form  to  be  removed  and  as  it  melts  is  drawn  by  suction  through  the  tube 
into  the  bulb  where  it  is  absorbed  by  the  cotton. 

A  device  of  this  kind  serves  its  purpose  admirably  but  it  lacks  simplicit}.  .An 
equally  efficient  method,  but  far  simpler,  has  been  suggested  by  someone  and  adopted 
by  the  writer.  It  consists  of  an  old  excavator  from  which  the  point  has  been  broken 
and  the  shank  slightly  roughened  with  a  file.  If  cotton  is  wrapped  in  a  spiral  about 
the  point  for  half  or  three-quarters  of  an  inch  and  the  shank  heated  some  distance 
farther  back,  the  point,  when  applied  to  the  wax  form,  will  melt  it  and  the  cotton 
instantly  absorb   it. 

In  this  way,  with  deft  handling  and  the  occasional  renewing  of  the  cotton,  any 
quantit}'  of  the  wa.x  form  may  be  removed,  and  any  shape  given  it.  In  fact,  the  wa.x 
which  is  usually  convex  on  its  under  side,  may,  by  this  method,  be  made  concave  or 
partially  hollow,  which  will  not  only  materially  lessen  the  amount  of  gold  used,  but 
also  aid  considerably  in  its  retention. 

The  main  object,  however,  in  rcmo^'ing  a  portion  of  the  wax  form  is  to  pro\'ide 
space  for  a  greater  quantity  of  the  non-conducting  cement. 

The  writer  has  also  found  it  of  advantage  to  groove  the  wa.x  form  for  retention 
purposes  instead  of  doing  it  later  on  the  cast  inlaj-.  To  do  it  after  the  gold  has  been 
cast  is  a  delicate  operation  sometimes  resulting  in  twirling  the  small  piece  out  of  the 
fingers  onto  the  floor  and  occasionally  wounding  the  fingers  when  a  small  circular 
saw  is  used. 

Grooves  are  easily  cut  in  the  wax  form,  if  the  sprue-wire  is  firmly  attached  to 
it,  by  drawing  a  fine  exca\'ator  along  the  surfaces  to  be  undercut.  A  fine  bead  will 
be  raised  on  each  side  of  the  groo\e  but  this  is  casih'  remoAcd  from  the  gold  surface 
after  casting. 

With  the  rapidly  extending  use  of  the  gold  inlay,  improved  methods  of  renio\'ing 
surplus  wax  from  the  form  and  of  grooving  its  sides  will  probably  soon  be  evolved 
from  the  brains  of  the  man^'  who  are  concentrating  their  thoughts  upon  the  further 
development  of  this  most  valual)le  method  of  tooth  preservation  and  restoration. 

— The  Garrelsonian. 


METHOD  OF  REPRODUCING  FLOWERS,  INSECTS  AND 
THE  LIKE  BY  CASTING 

By  T.  C.  Hutchinson.  D.D.S.,  Decorah,   Iowa. 

As  time  goes  on  the  science  of  art  and  invention  are  making  rapid  strides  towards 
producing  wonders  in  the  mechanical  Hne,  all  for  the  benefit  of  man,  to  aid  him  in 
accomplishing  work  more  rapidly,  in  doing  it  better,  and  at  the  same  time  making 
work  easier  on  the  man.  This  is  certainly  an  age  of  invention  and  the  dentist  who 
thinks  that  he  knows  all  about  the  casting  of  inlays,  crowns,  etc.,  has  yet  something 
along  these  lines  to  learn. 


With  the  invention  of  casting,  as  brought  out  by  Dr.  Taggart,  the  dentist  does 
his  work  more  rapidly  and  in  the  hands  of  the  average  man,  more  perfectly,  than  by 
the  use  of  former  methods  of  accomplishing  the  same  results.  The  dentist  has  more 
time  in  which  to  rest  and  occupy  his  time  with  things  of  interest,  and  the  writer 
knows  of  nothing  that  would  give  him  all  of  this,  better  than  the  making  of  metal 


METHOD  OF  REPRODUCING  FLOWERS,  ETC.,  B  Y  CASTING        21 1 


212  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

flowers,  etc.  To  practice  this  worlv  you  will  not  only  find  pleasure  in  the  work  but 
you  are  bound  to  learn  something  relative  to  your  work  in  casting  plates,  etc.  The 
illustrations  here  presented  of  the  cast  figures  will  give  you  an  idea  of  its  possibilities.. 

In  a  few  words  I  will  tell  you  how  to  go  at  it:  Take  any  flower,  no  matter  how 
delicate  it  may  be,  and  immerse  it  in  a  mild  solution  of  sandarac  varnish,  shaking  the 
surplus  off  by  taking  hold  of  the  stem;  then  mix  the  investment  material,  and  with  a 
camel's  hair  brush  paint  the  top  of  the  petals  as  you  would  your  wax  inlay.  Next,  if 
it  be  a  flower  of  several  petals,  pour  some  of  the  investment  material  in  the  palm  of 
your  hand  and  lay  the  flower  in  this  and  pour  more  investment  over  it;  jar  your  hand 
and  the  investment  will  fill  up  all  of  the  interspaces.  (Note  that  the  coating  of 
sandarac  attracts  the  moisture  of  the  material.)  Having  poured  some  investment 
in  the  bottom  of  your  flask,  take  the  partially  invested  flower  by  the  stem  and  lay 
in  the  flask  and  then  pour  the  flask  full.  Use  the  stem  of  the  flower  for  the  sprue. 
Make  the  crucible  form  for  3'our  metal  the  same  as  for  inlay  work. 

In  burning  out  the  flower,  which  is  placed  as  close  to  the  bottom  of  the  flask  as 
possible,  put  your  blast  heat  on  the  investment  instead  of  the  flask.  You  will  have 
to  make  a  cast  flower  to  learn  how  to  ascertain  the  time  required  to  burn  it  out.  With 
the  heat  directed  near  the  flower  one  should  not  consume  much  more  time  than  it 
would  take  to  burn  out  the  same  amount  of  wax. 


SOME  MORE  PROGRESSION 

By  R.  C.  Brophy,  M.D.,  D.D.S.,  Chicago,  III. 

The  dental  profession  is  a  progressive  body.  It  may  be  that  some  of  its  mem- 
bers did  not  vote  the  Bull  Moose  ticket  at  the  late  election,  but  it  is  probable  that  if 
they  did  not,  they  voted  for  Mr.  Wilson  through  a  belief  that  he  is  just  as  progressive 
as  is  Col.  Roosevelt. 

Especially  are  dentists,  as  a  body,  progressive  in  considering  new  ideas  pertain- 
ing to  practice.  Very  few  innovations  are  introduced  that  are  not  followed  by  a 
general  looking  up  and  taking  notice,  and  a  general  manifestation  of  a  purpose  to 
investigate;  but  when  a  new  idea  has  been  tested  and  found  worthy  of  adoption, 
they  exercise  no  less  progressiveness  in  acquiring  the  best  facilities  obtainable  for 
the  application  of  that  innovation  in  their  work  or  practice. 

It  has  been  observed  by  a  good  many,  however,  that  while  dentists  are  actuated 
in  their  progressiveness  in  adopting  new  methods  of  practice  by  a  desire  to  subserve 


the  best  interests  of  their  patients,  when  it  comes  to  the  matter  of  doing  the  work 
their  progressiveness  is  actuated  by  pure,  all-wool-and-a-yard-wide  selfishness. 
For  instance.  Dr.  j.  C.  Y.  Moore,  of  Aurora,  111.,  believes,  with  a  great  many  of  his 
brother  dentists,  that  the  best  way  to  conserve  the  interests  of  patients  who  have 
decayed  teeth,  in  a  large  percentage  of  cases,  is  to  make  and  insert  inlays  in  the 
cavities,  and  he  does  it. 

Dr.  Moore,  one  day,  made  an  inlay,  and  was  intently  at  work  finishing  it  to  the 
degree  usually  considered  before  insertion,  when  it  flew  from  his  fingers  and  alighted 
through  an  aperture  of  a  floor  register.  Dr.  Moore,  just  at  this  time,  began  to  forget 
about  his  patient,  and  commenced  to  think  about  Dr.  Moore.  The  inlay  was  re- 
covered. It  was  a  small  inlay,  and  as  Dr.  A'loore  pinched  it  harder  and  as  the  little 
disc  played  upon  the  inlay  and  upon  Dr.  Moore's  thumb  and  finger  in  a  mutual 
manner,  he  thought  more  and  more  of  Dr.  Moore.  The  patient  was  forgotten 
wholly,  brotherly  spirit  lay  dormant  in  his  breast,  and  no  thought  of  even  floor 
registers  or  sore  fingers,  other  than  his  own,  entered  or  emanated  from  Dr.  Moore's 
mind;  but  the  idea  was  then  and  there  born  therein  that  he  would  try  to  make  some 


214  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

kind  of  a  holder  that  would  hold  Dr.  Moore's  inlays  while  being  finished.  Dr. 
Moore  did  set  about  it,  and  the  process  of  evolution  finally  developed  a  perfectly 
practical  instrument,  an  efficient  little  device  for  that  purpose. 

It  was  a  clear  case  of  progress  being  pushed  ahead  by  pure,  unbridled  selfishness. 
No  consideration  of  the  uplift  or  maintenance  of  p.itients'  interests  nor  of  anyone 
else's  interests  save  Dr.  Moore's,  had  a  thing  to  do  with  the  pushing. 

As  a  matter  of  fact,  the  latent  disposition  of  Dr.  Moore  to  be  of  service  to  his 
brother  practitioner  by  offering  to  let  him  share  the  benefits  of  his  instrument  would 
have  continued  to  sleep  had  it  not  been  for  the  persuasion  of  the  writer. 

It  would  be  all  right  sometimes,  and,  as  a  matter  of  fact,  would  be  better  lots  of 
times  for  a  man  to  hide  his  light  under  a  bushel,  but  it  is  positively  wrong  for  a 
member  of  the  Christian-spirited  profession  of  dentistry  to  keep  as  good  a  thing  as 
Dr.  Moore's  inlay  vise  out  of  the  hands  of  his  professional  brother.  He  might  let 
him  chase  the  festive  collar  button  down  his  back,  under  the  dresser,  or  any  other 
place,  but  he  should  not  let  him  chase  the  inlay,  if  he  can  prevent  it,  as  Dr.  Moore 
can  do. 

The  cut  shows  the  two  styles  of  Dr.  Moore's  vise.  The  one  at  the  right  com- 
prised by  his  willing  but  inappropriate  fingers,  which  he  condemned,  and  abandoned, 
and  the  one  at  the  left,  much  simpler  in  construction,  yet  excelling  it  in  every  es- 
sential, which  he  has  substituted  therefor. 

It  is  unquestionable  that  dentists  feel  that  if  they  had  an  instrument  which 
would  hold  inlays  of  every  size  and  every  form  in  a  perfectly  rigid  grasp  on  the  end  of 
a  handle  nicely  fitting  the  clasped  hand,  and  thus  holding  it  without  contact  with 
the  fingers  or  obstructing  the  view,  operate  upon  the  outer  surface  and  margins,  a 
long  and  urgent  need  would  be  met. 

Having  been  instrumental  in  getting  Dr.  Moore  to  make  his  instrument  avail- 
able to  the  profession,  I  am  writing  this  because  I  regard  it  equally  important  that 
attention  of  the  profession  be  called  to  it. 


HOW  TO  OBTAIN  A  SMOOTH,  DENSE  SURFACE  ON  CASTS 

By  F.  L.  Olds,  D.D.S.,  Toledo,  Ohio. 

To  insure  smooth,  dense  surfaces  on  plaster  casts,  also  on  casts  made  of  invest- 
ment materials,  we  recommend  that  impressions  of  all-plaster  be  used;  or,  if  modelling 
compound  or  wax  be  used,  that  a  thin  layer  or  coating  of  plaster  be  applied  to  the 
surface  of  the  impression. 

To  prepare  the  impression  for  pouring  a  model  of  model-plaster  (New  York 
plaster),  for  vulcanite  work,  first  give  the  impression  a  thin  coat  of  shellac  varnish. 
When  this  has  become  dry,  which  it  will  in  about  thirty  minutes,  give  the  impression 
a  thin  coat  of  sandarac  varnish.  This  also  should  be  given  time  to  harden,  about 
twenty  minutes,  after  which  we  place  the  impression  in  water  and  allow  it  to  become 
saturated  before  pouring  the  model.  As  an  experiment,  take  any  piece  of  plaster 
that  has  been  lying  around  the  laboratory  for  a  few  hours,  and  put  it  in  water; 
bubbles  will  rise  on  the  surface  very  freely,  even  through  a  varnished  surface.  Now, 
if  freshly-mixed  plaster  or  investment  material  were  placed  in  a  dry  impression,  the 
same  thing  would  occur;  bubbles  would  come  from  the  surface  of  the  dry  plaster  and 
a  model  full  of  holes,  forced  in  by  these  bubbles  of  gas,  would  be  the  result.  The 
reason  for  using  the  varnishes,  as  stated,  is  that  the  shellac  acts  as  a  filler  on  the 
fresh  plaster  surface,  just  enough  being  used  to  fill  the  pores  and  stain  the  plaster 
to  a  slight  depth,  leaving  the  surface,  so  far  as  the  fine  lines  of  the  impression  are 
concerned,  just  as  it  was  before  varnishing. 

If  the  impressionweretobepouredatthisstage,  with  just  the  shellac  as  a  separating 
medium,  there  would  be  difficulty  in  separating,  as  the  plaster,  in  setting,  creates 
enough  heat  to  soften  the  shellac  and  thoroughly  glue  the  two  parts  together. 

Some  are  in  the  habit  of  using  oil  or  soap  to  prevent  this  sticking  together  of 
ihe  impression  and  model,  but  this  is  not  good  practice,  as  the  oil  or  soap  will  unite 
with  the  fresh  plaster,  and  a  very  poor  surface  on  the  model  is  sure  to  be  the  result. 
So  we  use  sandarac  varnish,  thin  sandarac  varnish,  as  a  second  coat  on  the  impres- 
sion. All  that  is  needed  is  just  enough  to  give  a  smooth,  glossy  surface.  We  prefer 
a  colored  varnish,  as  it  is  easier  to  ascertain  just  how  much  is  being  used. 

When  the  varnish  has  hardened,  place  the  impression  in  water  and  leave  it  there 
until  saturated,  so  that  no  bubbles  of  gas  will  rise  up  and  fill  the  surface  of  model 
with  the  holes  that  we  all  have  seen,  and  so  that  the  dry  plaster  will  not  take  up  some 
of  the  necessary  water  from  the  fresh  plaster,  and  give  us  a  porous  surface  of  poor 
quality. 

Sandarac  varnish  is  practically  inert  so  far  as  the  pouring  of  impressions  is 
concerned  and  can  be  separated  by  carving  away  the  impression  over  the  ridge  until 
the  stain  made  by  the  shellac  appears;  then  place  the  point  of  a  knife  under  the  edge 
and  gently  break  away  from  undercuts  and  around  teeth. 

After  separating  the  impression,  the  first  thing  to  do  is  to  give  the  surface  of  the 
model  a  good  coat  of  castgloss,  or  silex,  before  anjiihing  else  gets  onto  the  surface. 


216  PRACTICAL   MANUAL    OF    DENTAL    CASTING 

Hot  wax  or  grease  of  any  kind,  if  run  over  the  surface  before  applying  silex  prepara- 
tion, will  prevent  the  plaster  from  taking  up  the  silex,  and  a  rough,  porous  surface 
on  the  palate  of  the  plate  will  result. 

After  applying  castgloss,  wipe  the  model  dry  with  a  piece  of  cotton,  rubbing 
hard  enough  to  polish  the  surface  somewhat.  Hot  wax  or  any  other  material  may 
now  be  run  over  the  surface  of  the  model,  and  the  plate  will  still  come  out  with  a 
smooth,  clean  surface. 

For  models  of  investing  material  for  casting,  we  prepare  the  impression  the 
same  as  above,  with  the  exception  that  whatever  relief  is  desired  for  the  case  should 
be  carved  in  the  impression;  and  if  it  is  necessary  to  fit  the  plate  a  little  closer  at  the 
periphery,  just  add  a  little  wax  to  the  impression,  as  the  model  cannot  be  carved  when 
made  of  investment  material  without  making  a  rough  surface.  The  surface  of  a 
model  for  casting  should  be  left  just  as  it  comes  from  the  impression,  without  any 
alterations  whatever. 

The  surface  of  any  model  will  be  just  as  smooth  as  the  surface  on  which  it  is  poured. 
If  plaster  is  poured  onto  glass,  a  glassy  surface  is  the  result.  If  poured  on  a  rough 
surface,  the  surface  will  be  rough.  Therefore,  to  have  smooth  models  we  must  have 
smooth  impressions,  and  the  impression  must  be  treated  so  that  it  will  be  practically 
inert  so  far  as  the  pouring  of  freshly-mixed  plaster  or  investment  is  concerned. 


CASTING,  WITH  SPECIAL  REFERENCE  TO  CASTING  ON  PORCELAIN 

By  W.  C.  Gillespie,  D.D.S.,  Nashville.  Tenn. 

The  process  of  casting  metal  under  pressure  has  opened  the  greatest  field  of 
possibility  for  saving  and  restoring  teeth  that  the  dental  profession  has  come  into 
in  many  years.  The  casting  machine  stands  next  to  the  dental  engine  in  line  of  im- 
provement in  dental  equipment  and  in  variety  of  uses  to  which  it  may  be  put. 

There  are  countless  numbers  of  devices  for  casting  metal  under  pressure,  but 
all  are  variations  of  four  basic  types — those  that  utilize  centrifugal  force,  suction, 
compressed  air,  or  steam  pressure. 

The  application  of  pressure  casting — a  verv'  old  process — to  dental  art  will  raise 
the  general  average  of  tooth-savang  ability,  practical  merit,  and  artistic  product  of 
the  profession  because  it  will  enable  the  less  skilful  practitioners  to  form  in  plastic 
substance  and  reproduce  in  metal  better  dentures  than  the}'  were  able  to  do  direct 
in  the  more  refractory  substance. 

Casting  is  neither  an  experiment  nor  a  fad;  neither  can  it  be  conducted  on  the 
nickel-in-the-slot  basis.  A  few  porcelain  facings  or  teeth  and  a  little  scrap  gold 
dumped  into  the  machine  before  you  go  to  dinner  will  not  be  a  beautifully  finished 
bridge  when  you  return.  Brains  are  as  essential  to  successful  casting  as  a  properly 
constructed  casting  machine  and  necessary  materials. 

The  limitation  of  the  application  of  casting  depends  entirely  upon  the  ingenuity 
and  skill  of  the  one  who  employs  the  process  in  constructing  dental  restorations. 
By  this  means  anything  of  which  a  mold  may  be  obtained  may  be  reproduced  in 
metal  with  ease. 

Castings  consisting  entirely  of  metal,  such  as  inlays  or  all-gold  bridges,  may  be 
produced;  or  gold  may  be  cast  directly  in  contact  with  porcelain  surfaces  without  a 
previous  adaptation  of  backing.  A  simple  inlay  or  a  six-tooth  bridge  may  be  cast 
with  the  same  ease  and  same  amount  of  labor  in  so  far  as  the  casting  is  concerned- 

The  amount  of  time  required  to  cast  an  inlay  may  be  as  long  or  shorter  than 
would  be  required  to  condense  foil  in  the  same  ca\'ity;  but  the  physical  labor  is  not  a 
tenth  part  so  strenuous,  and  the  patient  will  rise  up  and  call  you  blessed.  More 
patients  ma}'  be  seen  in  a  day,  because  when  the  wax  model  is  obtained  the  patient 
may  be  dismissed  and  the  casting  made  when  there  is  nothing  else  to  do. 

The  advantages  of  cast  gold  over  welded  gold  are  too  well  understood  to  need 
comment,  and  where  the  inlay  is  preferable  to  a  condensed  filling  depends  entirely 
upon  conditions  to  be  met  in  each  case. 

The  time  required  to  construct  a  bridge  by  the  process  of  casting  is  \er\-  much 
less,  as  a  rule,  than  that  by  soldering,  and  the  time  and  labor  are  just  as  much  less 
as  would  be  necessary  to  do  the  things  avoided  by  the  process  of  casting — namely, 
greater  amount  of  grinding  porcelain  bodies,  backing,  making  dies,  swaging  cusps, 
waxing  cusps  in  position,  coaxing  solder  to  go  where  \v)u  wanted  it  and  grinding  off 
the  excess  solder  yuu  knew  \(>u  did  not  nt'ctl  i)ul  wtTe  afraid  nol  to  |)Ut  tlicre. 


218  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

The  time  required  to  wax  up,  invest,  drj'  out,  and  heat  up  is  the  same  for  either 
process;  but  the  actual  casting  requires  much  less  time  than  building  up  the  amount 
of  solder  would  do. 

Grant,  for  the  sake  of  argument,  that  the  time  required  by  both  processes  is  the 
same  for  a  given  case,  the  results  obtained,  labor  and  material  saved,  and  avoidance 
of  fatigue  and  discomfort  to  the  patient  place  casting  far  ahead  of  condensing  fillings 
and  soldering  crowns  and  bridges. 

The  dentist  who  casts  only  inlays  is  certainly  blind  to  the  possibilities  of  a  simply 
wonderful  and  wonderfully  simple  process  which  he  is  employing  only  in  its  most 
insignificant  application,  as  valuable  as  the  process  of  casting  inlays  may  be.  And 
the  dentist  who  does  not  cast  at  all  is  either  utterly  non-progressive  or  too  cautious 
for  his  own  and  his  patient's  best  interests. 

The  process  of  casting,  intelligently  employed,  is  thoroughly  applicable  to  the 
construction  of  shell  crowns,  all-gold  bridges,  retaining  appliances  for  regulations  or 
pyorrheal  teeth,  porcelain-faced  crowns,  bridges  wherein  porcelain  facings,  ordinary 
rubber-plate  teeth,  diatoric  teeth,  saddle-back  teeth,  removable-pin  crowns,  or  Logan 
crowns  are  employed  for  abutments  and  dummies  and  for  adapting  Logan  crowns 
to  roots. 

Any  type  of  porcelain  tooth  may  be  cast  upon  without  backing,  but  care  should 
be  exercised  not  to  use  a  tooth  with  pins  soldered  in  position  or  a  pin  of  composition 
metal  that  might  have  a  fusing  point  below  that  of  gold. 

Backing  as  employed  in  the  old  process  was  to  give  a  surface  upon  which  solder 
would  flow  evenly  and  not  ball  up.  It  had  little  to  do  with  the  prevention  of  check- 
ing of  porcelain,  however  contradictory  that  may  sound  to  the  teachings  and  ac- 
cepted theories  of  the  past.  A  direct  contact  of  porcelain  with  heat  or  flame  will 
not  cause  checking,  provided  the  cold  body  is  not  thrust  suddenly  into  a  flame  or 
furnace,  but  is  permitted  to  heat  gradually  at  first.  It  may  then  be  carried  to  a 
degree  considerably  above  the  fusing  point  of  pure  gold;  and  if  allowed  to  cool 
gradually,  no  checking  will  occur,  though  this  be  done  repeatedly. 

Borax  never  yet  caused  a  piece  of  porcelain  to  check,  except  indirectly;  yet  this 
statement  would  be  regarded  as  damning  heresy  bj'  the  old  masters.  These  things 
I  have  proven  bj'  hundreds  of  tests  and  experiments  during  a  practice  of  nine  years 
and  four  years'  experience  with  a  porcelain  furnace.  While  writing  this  paper  I 
have  had  in  my  electric  furnace  an  ordinary  plate  molar  tooth,  a  Logan  crown,  and 
two  diatoric  molar  teeth,  which  were  rolled  in  damp  powdered  borax  and  placed  in 
the  furnace  covered  with  a  layer  of  borax,  and  the  hole  in  the  diatoric  teeth  filled 
with  it.  A  nugget  of  pure  gold  was  placed  with  them  and  fused,  and  the  teeth  came 
out  without  a  check,  but  were  most  beautifully  glazed  on  surfaces  that  had  been 
ground  with  a  stone.  The  borax  may  unite  with  the  porcelain  and  cause  it  to  become 
more  brittle  if  carried  very  high,  but  the  experiment  is  cited  in  proof  that  it  does  not 
directly  cause  checking. 

Checking  of  porcelain  is  more  often  caused  by  unequal  expansion  and  contraction  - 
than  anything  else.  This  is  due  to  lack  of  uniformity  of  distribution  of  heat  or  the 
sudden  heating  or  cooling  of  the  surface  or  part  of  the  porcelain  body.  Different 
degrees  of  heat  produce  dift'erent  degrees  of  expansion  and  the  surface  or  some  portion 
of  the  body  of  porcelain  heating  or  cooling  faster  than  the  interior  or  some  other 
portion  of  the  mass;  and  porcelain  being  a  low  conductor  of  heat,  an  unequal  stress 
is  set  up  that  is  relieved  only  by  fracture. 


CASTING,  WITH  SPECIAL  REFERENCE  TO  PORCELAIN  219 

Fracture  is  also  caused  by  permitting  molten  solder  in  soldering  or  molten  gold 
in  casting  to  flow  around  an  edge,  and  in  the  contraction  of  cooling  a  grip  is  set  up 
that  will  break  any  porcelain  made.  Such  fracture  is  due  to  improper  waxing  up 
of  the  case  for  either  soldering  or  casting. 

It  is  also  claimed  that  a  metal  pin  in  a  porcelain  body — such  as  the  post  of  a 
Logan  crown — will  expand  faster  than  the  porcelain,  and  thus  cause  fracture.  That 
claim  sounds  plausible,  but  is  little  more  than  sound,  for  a  degree  of  heat  that  would 
expand  the  metal  sufficiently  to  do  that  would  have  already  fractured  the  porcelain 
by  suddenly  expanding  the  surface.  Also  where  there  is  a  post  baked  into  a  tooth 
heat  will  be  conducted  into  the  center  of  the  mass  by  the  metal  as  well  as  being  ab- 
sorbed by  the  surface,  and  the  distribution  will  be  more  uniform  than  if  the  post  were 
not  present.  If  the  heat  were  applied  to  the  post  directly  and  conducted  to  the 
interior  of  the  porcelain  while  the  surface  received  a  much  lower  heat,  then  the 
expansion  of  the  post  and  the  layer  of  porcelain  surrounding  it  would  be  faster  than 
that  of  the  surface'  and  fracture  would  result.  But  to  do  that  would  recjuire  con- 
siderable trouble  to  bring  about  something  nobody  wants. 

The  fractures  indirectly  caused  by  borax  are  brought  about  by  a  union  of  borax 
with  the  porcelain,  causing  it  to  lose  its  elasticity  and  become  more  brittle,  as  is  the 
case  when  gold  is  alloyed  with  some  base  metals.  This  loss  of  elasticity  renders  it 
less  capable  of  resisting  the  stress  of  expansion  and  contraction,  and  a  slighter  in- 
equality of  temperature  will  cause  a  fracture,  than  if  the  integrity  of  the  porcelain 
had  not  been  impaired. 

An  inlay  or  all-gold  casting  of  any  nature  may  be  successfully  cast  in  a  com- 
paratively cool  or  a  cold  mold,  as  is  proven  by  castings  of  iron  and  brass  foundries. 
But  to  cast  upon  porcelain  without  fracture  the  mold  must  of  necessity  be  brought 
to  such  a  temperature  that  the  porcelain  bodies  contained  will  be  subjected  to  no 
undue  strain  of  unequal  expansion  by  sudden  contact  with  molten  gold  of  much 
higher  temperature. 

The  investment  ring  is  readily  raised  to  a  red  heat;  but  investment  material  is 
a  low  conductor  of  heat,  and  several  minutes  will  elapse  before  the  heat  is  distributed 
throughout  the  mass.  So,  unless  sufficient  time  is  given,  the  porcelain  in  the  mold 
will  be  several  hundred  degrees  cooler  than  the  surface,  and  the  molten  gold  forced 
into  the  mold  will  fracture  the  porcelain  just  as  cold  glass  fractures  by  sudden  con- 
tact with  hot  water.  Get  the  porcelain  in  the  mold  thoroughly  hot  and  you  may  cast 
all  the  gold  on  it  necessary  for  any  denture  ever  put  in  the  mouth,  and  the  tiniest 
facing  will  never  be  checked  if  properly  waxed  and  invested.  No  flux  is  needed  for 
any  cast,  and  borax  when  fused  is  very  sticky  and,  uniting  with  the  investment,  inter- 
feres with  the  entrance  of  gold  into  the  sprue-hole. 

Logan  crown  joints  may  be  fitted  as  accurately  as  the  margins  of  inlays,  and  thus 
they  become  the  most  perfect  crown  restorations  known  to  the  profession,  and  may  be 
perfectly  adapted  to  roots  far  below  the  gum  line  all  around  or  at  any  point.  Molar 
stumps  in  the  same  condition  ma}'  be  easily  and  beautifully  restored  the  same  way 
by  placing  a  pin  in  each  canal  and  using  plate  teeth  with  pins  baked  in  or  diatoric 
teeth.  No  fear  need  be  had  in  casting  into  diatoric  teeth,  for  the  molten  gold  enters 
the  recess  in  them  at  its  maximum  expansion,  and  the  contraction  upon  cooling  makes 
the  post  thus  formed  slightly  smaller. 

Removable  pin  crowns,  such  as  Justi's,  the  Davis,  etc.,  have  no  lateral  openings, 
as  have  the  diatoric  teeth;  consequently'  the  molten  gold  will  not  enter  and  com- 
pletely fill  the  recess  provided  for  the  pin  because  there  is  no  avenue  of  escape  for 


220  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

the  air  caught  in  the  i^eccss.  It,  therefore,  is  better  to  remove  the  crown  from  the 
wax  before  investing,  and  the  porcelain  need  not  be  subjected  to  heat  at  all,  but  may 
be  cemented  on  the  post  after  the  gold  that  perfects  the  adaptation  to  the  root  has 
been  cast  onto  the  post. 

To  use  such  crowns  for  dummies,  clip  the  post  off  to  the  desired  length,  insert 
in  crowns,  wax  crowns  in  position,  chill  with  ice  water,  slip  crowns  off  posts,  cast, 
and  cement  crowns  in  place,  and  you  have  a  most  beautiful  and  practical  case. 
Crowns  and  dummies  thus  constructed  are  far  less  apt  to  break  away  than  those 
backed  and  soldered,  for  they  are  supported  by  perfect  contact  of  gold  at  every  point, 
while  a  backing  touches  only  here  and  there,  and  their  retention  depends  almost 
entirely  upon  the  strength  of  the  pins  baked  into  the  porcelain.  And  if  one  should 
break,  grind  up  and  cement  another  on  the  prj^t  left  standing. 

Pure  gold  should  be  used  for  inlays  and  22-karat  gold  for  everything  else.  In 
casting  inlays  and  shell  crowns  do  not  waste  gold  by  casting  them  unnecessarily 
thick.  Hollow  inlays  are  easily  made,  a  much  stronger  retention  is  secured,  and  a 
greater  thickness  of  cement  protects  the  pulp  from  thermal  irritation.  There  is  on 
the  market  a  device  consisting  of  a  hollow  metal  bulb,  with  small  extending  point, 
through  which  a  hole  extends  back  to  a  tube  to  which  is  attached  a  rubber  tube  with 
a  mouthpiece.  This  end  is  taken  in  the  mouth,  the  metal  bulb  is  heated,  and  when 
the  hot  point  is  touched  to  the  surface  of  the  wax  model  to  be  hollowed  out,  the 
melted  wax  is  instantly  sucked  back  into  the  bulb,  leaving  edges  as  clear-cut  as  if 
cut  with  a  knife.  The  same  thing  may  be  done  with  an  ordinary  hot-air  syringe  or 
chip  blower  having  a  bulbous  nozzle.  Solder  to  the  nozzle  the  shank  of  a  hypo- 
dermic needle,  having  bored  out  the  needle  with  a  small  drill.  Connect  the  rubber 
bulb  to  the  metal  tube  with  six  or  eight  inches  of  rubber  tubing,  so  the  bulb  may  be 
worked  with  one  hand  and  the  metal  point  directed  steadily  with  the  other.  Mount 
the  wax  model  of  the  inlay  on  the  sprue-pin  fixed  in  a  base  to  hold  it  steady,  and  then 
with  the  point  heated  suck  out  any  kind  of  undercut  or  hollow  you  desire. 

This  is  but  a  small  part  of  the  merits  and  possibilities  of  the  process  of  casting 
as  applied  in  dentistry;  but  too  much  time  cannot  be  taken  up  with  one  writing. 

— Dental  Headlisht. 


REMARKS  ON  CASTING 

By  Robert  N.   LeCron,   D.  D.  S.,  London,  England 

At  the  present  time  the  cast  plate  seems  to  hold  the  center  of  the  dental  stage 
amongst  the;  recent  reproductions  in  metal,  especially  in  England,  where  ijlate-work 
nourishes  to  a  greater  extent  than  in  any  other  country.  Hence,  those  interested 
in  the  exi)erimcntal  stages  of  casting  arc  called  n])on  to  answer  many  qucsli'tus  as 
(()  the  reasons  for  this,  that,  and  the  other  regarding  the  results,  possibilities,  and 
(he  future  of  the  cast-plate. 

riiis  branch  of  the  work  still  being  in  its  infancy  renders  some  of  the  cjuestions 
asked  practically  impossible  to  answer.  We  can  only  hope  to  arrive  at  definite 
conclusions  after  a  long  series  of  experiments  along  practical  lines,  not  alone  from  a 
demonstrator's  viewpoint  but  from  conclusions  based  upon  practical  work  in  the 
mouth  of  the  dentist  himself.  Casting  under  pressure  is  ancient,  yet  it  is  a  new  idea 
as  applied  to  dentistry'  today,  and  like  all  new  things,  is  being  worked  to  death, 
just  as  porcelain  work  was  misapplied  in  many  instances;  but  like  all  things  abused  it 
shall  find  a  place  amongst  the  branches  of  dentistry  according  to  its  merits  as  tested 
by  time. 

The  echo  from  all  sides  seems  to  be  complaint  as  to  the  casting  of  thin  gold  plate. 
It  seems  strange  that  so  much  stress  should  be  laid  upon  the  idea  of  a  thin  plate. 
True,  in  the  case  of  gold  the  thin  denture  is  that  which  is  desired  and  necessary,  but, 
nevertheless,  it  is  curious  that  a  thin  gold  plate,  full  or  otherwise,  should  be  the 
source  of  so  much  trouble  and  comment,  when  some  of  the  following  details  are  taken 
into  consideration.  From  a  casting  standpoint  only,  the  thicker  the  plate  or  the 
more  bulky  the  object  to  be  cast,  the  greater  the  air  space  or  cushion  within  the  mold 
to  get  rid  of,  after  the  wax  or  object  has  been  burned  out  and  the  greater  the  amount 
of  metal  necessary  for  the  casting  of  same,  and  in  like  proportion  the  greater  the 
surplus  metal  required,  consequently  a  greater  heat  must  be  used  to  melt  this  bulk 
of  metal  and  a  still  greater  care  to  see  that  it  is  not  only  molten  but  in  a  proper  con- 
dition to  flow  into  a  mold.  Then  too,  the  greater  the  mass  of  molten  metal  over  the 
gate  openings,*  especially  with  gold  or  any  of  the  heavier  metals,  the  greater  the 
liability  for  that  metal  to  sag  or  e\'en  flow  into  the  gate  or  gates  before  the  pressure 
is  applied.  Hence,  the  thinner  the  plate  or  the  object  to  be  cast  the  less  the  dif- 
ficulties and  the  easier  and  more  certain  the  result. 

One  of  the  most  important  factors  in  casting,  regardless  of  the  methotl  used, 
whether  it  be  by  gravitation  or  by  pressure,  is  the  getting  rid  of  the  air  from  within 
the  mold  quickly  and  with  the  least  possible  resistance  to  the  escape  of  that  air,  as 
the  molten  metal  enters  and  spreads  to  the  remote  parts  or  crevices  of  the  mold. 

While  watching  various  demonstrations  on  casting,  I  have  heard  the  question 
asked  and  have  been  asked  many  times  myself:  What  becomes  of  the  air  cushion 
within  the  mold?  Demonstrators  must  have  an  answer  ready  at  all  times,  otherwise 
they  are  liable  to  find  themseh'es  in  an  awkward  position.  Some  insist  that  upon 
heating  up  the  case  the  air  within  the  mold  becomes  rarified — and  so  it  does;  but  not 
to  the  extent  of  producing  a  vacuum,  as  sometimes  implied,  or  anything  approaching 

The  words  gate,  lead  and  runner  in  this  article  are  used  to  express  what  is  generally  termed  sprue 


222  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

such  a  highly  rarefied  condition.  If  it  were  possible  to  produce  a  vacuum — the 
casting  apparatus  with  the  method  of  melting  the  metal  in  a  crucible  directly  over 
the  gate  openings  would  be  practically  useless.  If  such  was  a  fact,  upon  melting 
the  metal  upon  a  flat  crucible-like  surface  of  one  of  these  highly  heated  cases,  one 
would  naturally  expect  bits  of  the  molten  metal  to  be  drawn  into  the  mold  as  parts 
melt  and  fall  away  from  the  yet  unsettled  portion,  instead  of  melting  gradually  and 
remaining  in  a  liquid  mass  over  the  gate  openings,  until  a  positive  pressure  be  applied. 

Perhaps  the  above  is  the  cause  of  some  failures,  where  the  case  is  heated  until 
it  glows  red  from  within  through  the  gate  openings.  In  speaking  of  extensive  castings 
where  fifteen  or  more  hundredweights  of  heavy  metal  are  used,  capillary  contraction 
is  not  sufficient  to  cause  the  molten  mass  to  globuJate  to  any  great  extent,  far  less 
overcome  the  suction  from  beneath,  caused  by  the  supposed  vacuum  within  the 
mold. 

The  air  surrounding  tlic  molten  mass  becomes  more  and  more  rarefied,  it  is  true, 
as  the  intensity  of  the  heat  increases  for  melting  purposes,  and  no  doubt,  theoreticalh' 
overcomes  and  counteracts  the  vacuum  within  the  mold,  which  space  has  had  a  greater 
or  less  opportunity  to  cool  while  melting  the  ingot.  (At  least,  this  is  one  explanation 
set  forth.)  If  the  above  be  a  correct  theory,  the  question  then  arises:  Why,  if  the 
mold  be  ventilated,  is  the  molten  metal  more  liable  to  sag  into  the  gate  openings,  or 
to  actually  flow  into  the  mold  without  the  application  of  pressure  providing  the  mold 
be  sufficiently  vented  than  in  a  case  where  mechanical  vents  are  lacking? 

For  instance,  before  Doctor  Taggart  conceived  the  idea  of  casting  as  it  is  now 
applied  to  dentistr>',  some  were  casting  into  matrices.  Shortly  after  this  method 
was  given  out,  but  not  known  in  detail  to  the  profession  generally,  many  more  were 
experimenting  along  these  lines  of  gravitation. 

This  method  is  known  to  all  and  simply  consists  of  a  mold  with  a  vent  leading 
from  the  same  to  the  outside  of  the  investment,  and  a  large  gate  opening  into  the 
same.  The  metal,  instead  of  being  melted  over  the  gate  opening,  was  melted  in  a 
crucible  to  one  side  with  a  lead  or  avenue  to  the  large  orifice  of  the  gate  opening. 
As  soon  as  the  molten  metal  was  in  the  proper  condition  to  flow,  the  case  was  tipped 
to  one  side  allowing  the  metal  to  flow  into  the  gate  or  runner  and  gravitate  thence 
into  the  heated  mold.  This  method  was  applied  only  to  small  castings,  and  the 
success  of  the  same  depended  not  only  upon  the  thorough  heating  up  of  the  case,  a 
large  gate  and  plenty  of  metal,  but  also  upon  the  vent  opening  to  allow  for  the  escape 
of  the  air  from  within  the  mold.  These  cases  were  heated  extremely  hot,  yet  the 
rarefication  of  the  air  within  the  mold  thus  brought  about  was  not  sufficient  to  secure 
a  perfect  result  in  any  instance,  unless  there  was  a  vent  from  the  mold  to  the  outside. 
One  realizes  quite  readily  how  difficult  it  is  to  pour  water  or  any  liquid  into  a  bottle 
or  closed  flask  where  the  air  contained  within  must  escape  from  the  same  aperture 
through  which  the  liquid  is  being  poured.  If,  however,  there  be  another  outlet  to 
the  atmospheric  pressure  within  the  flask  the  procedure  is  quite  simple. 

With  castings  such  as  poured  by  the  working  jewelers  in  cuttle-fish  bone,  and 
those  on  a  larger  scale  in  foundries  into  molding  sand,  some  of  the  important  details 
are  as  follows:  Sufficient  vents,  a  large  runner,  depending  on  the  size  and  the  complica- 
tion of  the  casting  in  hand,  and  sufficient  bulk  of  metal  in  a  thoroi:ghly  molten  condition 
to  flow.  At  least,  these  were  the  prime  factors  most  impressed  upon  my  mind  while 
taking  a  course  in  a  molding  shop.  All  necessary  on  account  of  the  mold  being  cold, 
and  the  flow  of  the  metal  depending  alone  upon  its  own  weight  and  surplus  behind 


REMARKS  ON  CASTING  22;j 

called  the  runner  and  sulhcicnt  access  to  all  parts  of  the  mold  to  enalile  the  liquid 
mass  to  spread  quickly  co  all  parts  without  interference  from  the  air  within. 

Though  a  mold  be  well  vented,  if  it  be  filled  from  the  top  the  casting  is  liable  to 
be  full  of  blow  holes.  In  such  cases  dense  castings  may  be  obtained  by  giving  an 
extra  length  at  the  top  of  the  mold  away  from  the  runner — the  unsound  portion  being 
thus  formed  in  this  extra  length  and  cut  away  afterwards  as  the  deadhead. 

In  casting  a  metal  under  pressure,  the  conditions  are  ditTerent  and  allow  and 
necessitate  certain  changes  or  deviations  from  the  old  method:  however,  it  is  always 
well  to  bear  in  mind  the  law  of  gravitation  and  the  details  go\erning  cheoplastic  art. 

On  account  of  the  metal  being  melted  in  a  crucible,  directh'  over  the  opening  or 
lead  into  the  mold,  instead  of  pouring  the  liquid  mass  into  a  runner — this  lead  or  gate 
must  be  much  smaller  in  diameter.  If  too  large,  the  metal  is  liable  to  sag  into  the 
same;  if  too  small,  the  construction  offers  too  great  an  obstruction  to  the  flow  of  the 
metal.  With  small  castings,  it  is  remarkable  what  a  small  gate  opening  the  metal 
may  be  forced  through. 

I  have  been  trying  to  determine  by  a  series  of  experiments,  not  }et  completed, 
the  size,  length  and  number  of  the  gate  wires  necessary  for  the  various  castings  in  the 
different  metals;  for  each  metal  allows  of  a  different  treatment.  With  aluminum  or 
any  of  the  lighter  metals,  most  any  size  gate  seems  to  answer  the  purpose;  but  as 
there  is  no  tendenc>-  for  these  mecals  to  sag,  a  very  large- gate  will  be  found  most 
useful.  The  heavier  metals  in  large  castings  require  more  care  in  the  selection  of 
the  gate  wires;  with  such  metals  as  tin  and  Watt's  metal  that  melt  at  a  low  temper- 
ature and  remain  liquefied  for  some  considerable  time,  smaller  gates  may  be  used 
than  with  the  same  case  in  gold  that  solidifies  quickly. 

If  attempting  a  large  casting  in  gold  through  one  lead,  there  i?  an  inlluence 
towards  using  a  large  gate  wire,  thereby  rendering  a  failure  more  possible.  Hence  I 
prefer  to  use  two  or  more  smaller  gates  leading  to  various  parts  of  the  mold  to 
minimize  uncertainties.  Casting  a  metal  into  a  mold  in  a  bulk  is  quite  different  from 
that  of  casting  the  same  quantity  where  it  must  spread  for  some  distance  from  its 
entrance  into  the  mold. 

In  short,  with  the  data  to  hand.  I  can  but  sa>'  that  I  adhere  to  the  following 
details  as  nearly  as  possible  until  I  satisfy  myself  more  fully  on  this  subject,  /.  e., 
the  heavier  and  the  greater  the  bulk  of  the  metal  to  be  used  with  the  exception  of 
tin  and  Watt's  metal  and  similar  metals  and  the  thinner  the  object  to  be  cast,  the 
smaller  the  gate  openings  and  the  greater  the  number  of  the  same  radiating  from  a 
common  center  to  various  parts  of  the  mold,  and  last,  but  by  no  means  least,  the 
flatter  the  crucible  or  surface  upon  which  the  metal  is  to  be  melted. 

Certain  stress  has  been  laid  upon  the  subject  of  ventilation,  yet  a  few  more 
words  may  lie  added.  There  are  m.any  methods  whereby  this  important  procedure 
may  be  accomplished.  With  small  work,  the  porosity  of  the  investment  should  be 
quite  suiificient.  By  the  word  small  I  not  onK'  imply  inla\s,  but  crowns,  bridges — 
in  fact,  any  design  within  the  radius  of  two  and  a  half  inches.  Larger  objects  may 
be  cast  relying  upon  the  same  escape  for  the  internal  gases,  in  which  cases  the  pro- 
cedure of  investing  is  an  important  detail,  /.  f.,  to  be  certain  that  the  distance 
through  the  investment  from  the  top  down  to  the  mold  is  greater  than  the  distance 
from  the  mold  down  through  the  base,  and  where  the  metal  must  flow  for  some  con- 
siderable di.stance  from  the  entrance  cf  the  gate  openings  into  the  molds,  to  be  careful 
that  these  remote  parts  be  quilr  near  to  the  base,  so  that  as  the  metal  enters  and 
spreads  to  those  distant   parts  the  air  contined  therein  is  forced  thnuiL;h  but  a  \ery 


224  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

thill  layer  ot  inxestincnt  to  the  outside  of  the  cup;  and  the  pressure  from  abo\e  has 
little  chance  of  driving  air  through  the  thick  investment  over  these  parts  before  the 
metal  spreads  to  the  same. 

The  air  within  the  mold  is  either  taken  up  by  the  investment  similar  to  a  sponge, 
absorbing  water,  and  like  the  sponge,  it  has  a  limited  capacity,  after  which  the  re- 
maining air  must  be  driven  through  the  investment  to  the  outside  or  remain  within 
with  the  liability  of  causing  blow  holes  by  reacting  upon  the  molten  mass  or  defects 
by  not  allowing  the  metal  to  spread.  Any  air  driven  out  into  the  investment  is 
driven  there  under  pressure;  hence  to  further  assist  the  escape  of  internal  air  or  gases 
I  find  it  quite  convenient  to  perforate  the  lower  strata  of  investment  through  into 
the  mold  with  a  fine,  smooth  broach  before  the  wax  or  object  is  burned  out.  To 
leave  these  mechanical  vents  open  is  liable  to  cause  trouble  if  a  heavy  metal  is  to  be 
used;  by  rubbing  some  of  the  surplus  investment  over  the  base  these  holes  or  vents 
may  be  temporarily  stopped  to  hold  the  air  cushion  within,  which  in  turn  prevents, 
along  with  other  details,  the  metal  from  sagging  into  the  open  gate  while  being  melted. 
As  soon  as  the  pressure  is  applied  for  casting,  these  slight  stoppings  blow  out,  leaving 
open  rents  through  which  the  air  may  pass  with  the  least  possible  resistance. 

If  there  is  any  one  detail  in  the  mechanical  process  more  important  than  another, 
I  should  say  that  it  is  the  melting  of  the  metal.  There  is  a  certain  condition  of  a 
molten  metal  at  which  that  respective  metal  will  cast  to  the  best  advantage,  and  it 
is  not  the  boiling  point.  Any  ordinary  blow-pipe  may  be  used  that  will,  with  the 
proper  manipulation,  melt  the  metal  quickly  with  a  strong  blue  flame;  in  no  instance 
should  a  large  smoky  flame  be  used,  for  it  only  tends  to  oxidize  and  spoil  the  working 
of  the  metal.  Once  the  metal  has  been  melted,  one  should  not  be  too  anxious  to 
cast,  but  should  employ  a  small  soft  flame  for  a  short  time  upon  the  already  molten 
mass  until  certain  it  is  in  the  proper  condition  to  flow  into  a  mold.  Take,  for  in- 
stance, in  the  ordinary  casting  of  zinc  and  lead  for  dies,  etc.,  considerable  care  is 
taken  that  the  molten  metal  is  not  bubbling  from  being  too  hot  and,  on  the  other 
hand,  not  sluggish  from  being  too  cold  before  pouring.  If  the  metal  be  in  the  proper 
condition  one  need  not  be  in  a  great  hurry  to  apply  the  pressure,  for  it  will  remain  in 
a  liquid  form  some  considerable  time. 

In  conclusion,  simply  because  the  molten  metal  is  to  be  driven  by  force  into  the 
mold  is  not  sufficient  reason  for  being  careless  about  the  melting  of  the  metal,  even 
in  such  simple  castings  as  inlays,  and  yet  expect  an  apparatus  of  any  description  to 
duplicate  perfect  castings  under  such  adverse  conditions. — Dental  Brief. 


PLATE  CASTING  BY  THE  VACUUM  PROCESS 
By  W.  L.  Harpel,  D.  D.  S.,  and  F.  L.  Olds,  D.  D.  S. 

The  first  step  in  plate  casting  is  to  obtain  a  perfect  plaster  impression.  All 
relief-work  necessary  must  be  done  on  the  impression,  because  the  model  cannot 
be  altered  after  pouring. 

When  the  impression  has  set,  apply  a  coat  of  Separlac,  filling  the  pores  of  the 
plaster,  thus  producing  a  smooth,  glossy  surface.  Twenty  to  thirty  minutes  should 
be  allowed  for  drying  the  varnish. 

All  air  must  be  expelled  from  the  impression.  To  do  this,  i)!acc  in  water  and 
allow  it  to  remain  there  until  Ijubbling  stops. 

Models  should  be  made  from  Imperial  Investment  Compound.  There  may  be 
other  good  compounds  obtainable,  but  we  know  of  none  that  compares  at  all  with 
Imperial  for  the  making  of  models.  The  cost  is  so  trifling  that  it  is  not  worth  while 
to  experiment. 

The  proper  mixture  is  one  part  water  to  four  parts  investment.  See  that  the 
mix  is  thorough.  Chemical  action  must  take  place  within  every  atom  of  the  in- 
vestment. Do  not  beat  or  stir  the  mixture  violently;  spatulate  it  gently  but  con- 
tinue until  a  thorough  amalgamation  has  taken  place.  Otherwise  bubbles  will 
form  and  the  cast  cannot  be  satisfactorv. 


Plate  1 — The  Finished  Model 


Plate  2 — Model  \Va-xed 


After  the  model  has  been  poured  and  allowed  to  harden,  requiring  ten  to  fifteen 
minutes,  separate  and  trim  as  thin  as  can  safely  be  handled,  allowing  flanges  to  pro- 
ject as  shown  in  illustration.  The  smooth  surface  of  the  model  must  be  maintained; 
therefore  do  not  attempt  to  make  any  alterations  on  the  model.  A  little  Canton 
graphite  rubbed  over  the  casting  surface  of  the  model  with  the  finger  will  add  to  its 
smoothness,  anci  insure  a  bright,  polished  surface  on  the  cast. 

Thin  base-plate  wax  is  to  be  adapted  to  the  model,  allowing  it  to  cover  it  a  little 
higher  than  the  plate  is  to  be  v.'hen  cast.  In  trimming  the  sheet,  be  guided  by  the 
height  of  the  plate,  both  buccally  and  labially.  Use  a  wax  that  does  not  become 
quite  brittle  when  cold.  A  light-colored  translucent  wax  is  to  be  preferred.  Do  not 
use  highly-colored  or  dirty  wax,  as  it  is  sure  to  leave  a  residue  when  removed  by  heat; 
likely  to  cause  holes  in  the  plate. 


226  PRACTICAL    MANUAL    OF    DENTAL    CASTING 

Wax  must  be  carefully  sealed  to  model  all  around  with  a  hot  spatula;  otherwise 
investment  may  work  in  between  the  wax  and  model. 

Lay  a  ruler,  with  beveled  edge,  the  long  way  of  a  sheet  of  wax,  and  with  a  warm 
knife  held  against  the  edge  of  the  ruler  at  an  angle  of  45  ,  cut  strips  of  the  wax  }/^- 
inch  wide  and  full  length  of  the  sheet. 

Warm  the  strips  of  wax  slightly,  and  lay  around  buccal  and  labial  edges  of  wax 
base  where  the  pencil  mark  shows  through  base  plate,  to  form  outer  rim.  Turn 
around  heel  of  plate  over  tuberosities  and  around  palatal  portion  to  form  inner  rim. 
These  strips  of  wax  will  meet  at  center  of  plate.  Seal  strips  down  with  a  hot  spatula 
and  a  little  extra  wax. 

The  beveled  edges  of  the  strips  must  be  placed  next  to  the  surface  upon  which 
attachment  is  to  be  made.  See  that  the  wax  rims  thus  formed  present  perfect 
under-cuts.  Cut  small  lugs  of  wax  and  place  them  where  they  will  give  best  at- 
tachment, or  the  metal  may  be  spurred  or  picked  for  vulcanite  attachment  after 
casting. 

Cover  wooden-sprue-block  with  a  thin  coating  of  wax  to  facilitate  removal  from 
the  investment;  cut  four  strips  of  base  plate  wax,  one-half  to  three-quarter  inches 
long  and  three-eighths  wide  and  attach  to  wooden  sprue-block  in  such  position  that 
one  will  connect  with  the  wax  base  plate  at  each  of  the  tuberosities  and  the  others 
palatally  to  form  gates.  This  wax  should  be  of  same  thickness  as  that  used  for 
the  plate. 

To  determine  the  distance  of  sprue-block  from  wax  model,  place  model  on  flat 
outside  surface  of  flask  and  within  one-half  inch  of  bottom  or  small  end,  and  attach 
wax  strips  so  that  sprue-block  will  be  even  with  top  of  flask. 

The  gates  should  not  exceed  three-eighths  inch  in  width,  as  ,  if  wider,  the  metal 
may  be  carried  down  by  gravity  before  the  valve  is  opened,  spoiling  the  cast. 

Place  model  with  wax  base  and  sprue-block  in  water  and  let  it  soak  until  all 
bubbling  has  stopped. 

We  are  now  ready  to  invest  the  case  for  casting;  but,  before  going  further,  we 
must  be  sure  that  we  are  ready  to  proceed  with  the  operation  at  once.  The  case 
must  be  heated  up  and  cast  as  soon  as  invested;  otherwise  checks  are  sure  to  occur, 
and  the  cast  will  be  spoiled. 

Standard  Investment  Compound  (not  Imperial)  is  recommended  for  all  casting 
operations  (not  for  models).  It  is  finely  ground,  yet  porous,  withstands  the  action 
of  heat  better  than  others  and  reproduces  the  finest  lines  with  the  utmost  nicety. 

When  ready  to  invest,  not  before,  mix  a  sufficient  quantity  of  Standard  Invest- 
ment to  a  consistency  that  will  just  admit  of  its  being  poured  from  the  bowl.  Paint 
the  model  thoroughly  with  the  mixed  investment,  using  a  fine  brush,  being  careful 
to  fill  all  undercuts.  Fill  the  plate-flask  three-quarters  full  of  the  investment,  place 
the  model  therein,  and  gently  press  to  place. 

The  model  should  come  to  within  one-half  inch  of  the  bottom  of  flask. 

The  flanges  allowed  to  project  at  the  sides  near  the  labial  end  of  the  model  will 
prevent  its  going  into  the  flask  too  far. 

Be  sure  to  get  model  as  nearly  into  center  of  flask  laterally  as  possible. 

When  thoroughly  set  and  dry,  which  should  be  in  15  to  20  minutes,  slightly 
concave  the  investment  at  the  bottom  or  small  end,  of  flask,  place  in  absolutely  clean 
boiling  water  and  let  it  remain  until  the  wax  is  softened;  a  little  gentle  pressure  with 
an  old  rubber  file  or  long  instrument,  on  the  sprue-block  will  cause  it  to  float  out. 
Remove  case  from  water  at  once  and  l)rcak  waay  any  frail  pieces  of  investment  so 


PLATE  CASTING  BY  THE   VACUUM  PROCESS  227 

that  they  may  not  drop  into  the  sprue  holes  (openings  formed  by  wax  gates).  The 
remaining  wax  can  easily  be  washed  out  by  holding  the  case  slightly  oblique  and  pour- 
ing a  small  stream  of  absolutely  clean  boiling  water  into  upper  gate.  Any  tin 
receptacle  with  a  small  hole  punched  through  the  bottom  at  one  of  its  edges  makes  a 
good  vessel  for  the  purpose.  Care  must  be  taken  to  exclude  all  dirt  from  the  mold. 
To  burn  out  the  wax  place  point  of  knife  under  edge  of  sprue-block  and  carefully 
lift  from  place;  then  heat  on  bracket  of  adjustable  stand  very  slowly  at  first,  keeping 
the  flame  low  until  steam  no  longer  rises  from  the  case.  Then  increase  the  flame 
until  it  is  giving  all  the  heat  po.ssible,  holding  it  there  until  the  wax  has  entirely 
burned  out  and  the  case  is  heated  as  directed  above. 


Plate  3 — Model   Mounted  on  Sprue-former,   Showing  Gates 

If  the  boiling-out  process  is  used,  immediately  after  boiling  place  over  a  slmv 
fire,  allowing  it  to  remain  until  all  steaming  has  stopped,  occasionally  turning  the 
fiask.  Test  for  moisture  with  mirror.  When  no  moisture  appears  place  directly 
over  a  spreading  flame.  Cover  with  an  inverted  pan  to  insure  even  distribution  of 
heat,  occasionally  turning  flask  until  it  is  a  dull  red  all  over  and  stays  so.  Do  not 
permit  flame  to  strike  directly  upon  the  investment  at  any  time. 

When  the  case  has  been  carried  to  this  point  put  an  ingot  of  Aerdentalloy  or 
double  refined  Aluminum  in  the  meltmg  crucible  and  set  above  flame  with  Economy 
Heat  Cap  over  it.  Now  invert  flask  and  let  flame  come  in  contact  with  crucible 
surface  while  metal  is  melting. 

The  overheating  of  the  metal  will  ruin  it,  and  the  melting  process  must  be  care- 
fully watched.     A  blowpipe  flame  should  not  be  used  directly  on  the  metal. 

When  metal  has  fused  (fused,  remember,  not  burned),  pump  up  the  vacuum  to 
twenty  or  twenty-five  inches;  take  case  from  fire  and  place  on  bed-plate  of  appliance, 
first  examining  bottom  of  flask  and  bed-plate  to  see  that  there  is  nothing  to  prevent 
perfect  contact.     Turn  valve  to  see  if  contact  is  perfect. 

When  contact  is  perfect,  the  hand  of  the  indicator  will  fall  \qv\  slowly;  but  if 
contact  is  not  perfect  the  hand  will  fall  rapidly. 

Grasp  the  crucible,  containing  the  molten  metal,  with  a  pair  of  I'nixersal 
Laboratory  Pliers  and  quickly  jiour  the  metal  into  the  funnel-shaped  depression  in 
the  top  of  flask  (called  crucible).  When  I  he  nulai  is  ail  in  and  the  s[)rue  holes  co\ered 
turn  the  \'alve. 


228  PRACTICAL   MANUAL   OF    DENTAL    CASTING 

The  pouring  of  the  metal  and  opening  of  valve  should  be  made  almost  one  con- 
tinuous movement  as  a  very  little  delay  at  this  point  will  spoil  the  case.  Never 
turn  the  valve  until  all  the  metal  is  in  the  crucible,  but  do  not  delay.  Prompt, 
decisive  action  is  necessary. 

The  metal  chills  very  rapidly,  and  both  case  and  flask  should  be  nearly  the 
temperature  of  fused  metal  when  pouring. 

Remember,  sharp  holes  in  the  plates  indicate  heating  too  fast  and  thereby  ex- 
ploding pieces  off  the  investment  on  the  inside. 

Round  holes  indicate  that  the  case  was  not  hot  enough  before  casting,  or  at  the 
time  the  cast  was  made.  Holes  along  edges  indicate  that  too  little  metal  has  been 
used. 

Let  the  case  stand  before  opening  until  it  has  cooled  enough  to  be  picked  up  by 
the  naked  hand.  Remove  case  from  flask.  Cut  off  sprues,  preferably  with  saw. 
finish  with  files,  stones,  emerj'  paper,  felt  cones  and  pumice,  and  polish  with  any  good 
material.  Clean  and  oil  the  flask  on  the  bottom  to  prevent  rusting  while  flask  is  not 
in  use. 

We  do  not  recommend  the  casting  of  teeth  direct  to  metal  plates,  although  it 
can  be  done.     The  vulcanite  attachment  is  preferred  as  safer  and  better. 

Some  Important  Suggestions  * 

Be  sure  to  test  the  appliance  for  leakage  before  attempting  to  cast.  To  do  this, 
pump  up  the  gauge  to  fifteen  or  twenty  inches;  put  flask  or  ring  on  bed-plate  and 
firmly  closing  the  larger  opening  with  the  palm  of  the  hand,  open  the  valve;  the 
hand  of  the  indicator  will  remain  stationary,  provided  contact  is  perfect  and  there  is 
no  leak.  Otherwise  the  hand  will  fall,  rapidly  or  slowly,  depending  upon  the  nature 
of  the  leak.     If  there  is  a  leak,  find  it  and  remedy  it  before  going  further. 

If  the  flask  has  become  oxidized  on  bottom  and  that  is  the  point  of  leakage 
(which  usually  is  the  case)  mix  some  fine  carborundum  powder  with  oil  on  a  piece 
of  plate  glass  (not  ordinary  glass  because  its  flatness  cannot  be  depended  upon), 
and  grind  bottom  surface  of  flask  on  glass  until  perfectly  true  and  clean.  Also  oil 
contact  surface  of  bed-plate. 

Do  not  let  your  rings  or  bed-plate  become  rusty  or  dirty;  oil  them  immediately 
after  using  and  cover  bed-plate  when  not  in  use.  Bear  in  mind  that  neglect  in  keep- 
ing clean  the  bed-plate  and  neglecting  to  keep  the  rings  flat  on  the  bottom  mean 
failure. 

If  the  leakage  is  not  found  to  be  as  indicated  above,  place  a  little  saliva  or  soap 
suds  around  the  different  joints  between  tank  and  attachments  and  around  air  cocks; 
then  pump  up,  place  the  palm  of  hand  over  bed-plate  and  turn  the  valve.  The 
leakage  will  cause  the  saliva  or  suds  to  be  drawn  in.  If  the  leak  is  at  a  joint,  unscrew 
the  attachment,  mix  a  little  dental  cement  and  place  it  on  both  connections  and 
screw  up. 

Should  there  be  leakage  of  air  about  an  air  cock,  remove  the  thumb  control  by 
taking  out  the  screw  on  rear  end  and  removing  cap-washer,  when  a  light  tap  will 
loosen  it.  (Jive  all  contact  surfaces  a  light  coating  of  special  vah'e  wax,  supplied 
with  the  outfit.  .Additional  quantit\'  can  be  procured  from  the  manufacturer  (price, 
lU  cents  per  box). 

Should  it  still  be  difficult  to  maintain  a  vacuum  in  the  cylinder,  the  trouble  may 
be  caused  by  the  collection  of  dust  and  wax  about  the  pump  valve.  Remove  pump 
and  valve;   clean  all  parts,  valve,  valve-seat  and  hexagon  cone  tip  with  gasoline  and 


PLATE  CASTING  BY  THE   VACUUM  PROCESS  220 

replace.  If  this  docs  not  rcnicd}-  the  difficult)-,  procure  a  new  \al\e  from  the  man- 
ufacturer (price,  10  cents);  rcmo^■e  the  pump,  take  off  the  nut  on  its  inner  end,  and 
the  valve  will  be  found  in  the  nut.  The  nut  is  of  soft  metal  and  must  be  handled 
carefully.     Use  a  true  wrench,  with  sharp  square  jaws. 

Replace  the  valve  removed  with  the  new  one,  being  careful  to  insert  so  that  the 
cork  in  the  valve  will  impinge  against  the  cone-point  of  the  nut  when  air  is  exhausted 
from  the  Appliance.  Smear  a  very  little  paint  or  white  lead  on  the  thread  of  the 
nut,  and  screw  to  place. 

The  pump  plunger  should  be  oiled  occasionally  through  the  holes  through  which 
the  air  escapes. 

Slight  leakage  of  air  into  the  tank  is  liable  to  occur  owing  to  the  tremendous  air 
pressure  if  an  attempt  is  made  to  hold  the  vacuum  too  long.  It  is  practicallv 
impossible  to  hold  a  vacuum  for  any  great  length  of  time.  The  vacuum  should  be 
produced,  therefore,  just  previous  to  melting. 

If  the  indicator  of  the  gauge  does  not  register  correctly,  remove  the  rim,  the 
glass  front  and  the  face  of  the  indicator.  This  allows  free  access  to  the  simple 
inner  mechanism  of  the  gauge.  In  re-assembling,  put  indicator  or  hand  of  gauge 
over  its  pivot  with  the  point  just  below  the  pin  to  the  left.  Press  the  indicator 
firmly  to  place,  then  spring  the  end  over  the  pin  and  replace  glass  and  rim.  If 
necessary  to  remove  the  gauge,  first  take  out  the  glass  to  prevent  breakage;  then 
place  a  light  wooden  strip  across  the  face  of  the  gauge,  resting  on  the  rim,  and  another 
across  the  back.  These  strips  should  project  beyond  the  periphery  of  the  gauge 
sufficiently  to  give  leverage  and  act  as  a  wrench.  Then  unscrew  the  gauge  from 
its  seat. 


INLAY  CASTING  BY  THE  VACUUM  PROCESS 

By  L.  W.  Strycker,  New  York 

Prepare  cavity  so  that  wax  will  draw  from  it  without  dragging  or  becoming 
distorted.      If  properly  prepared,  the  wax  will  draw  out  in  one  way  only. 

Freely  moisten  cavity,  or  use  a  very  little  alboline,  to  prevent  wax  model  from 
adhering  to  walls.  Be  careful  to  get  none  of  the  lubricant  on  point  of  wax  to  which 
sprue  is  to  be  attached,  nor  upon  the  sprue  wire. 

Soften  Standard  Inlay  Wax  and  force  into  cavity,  being  sure  that  it  goes  firmly 
to  every  portion;    if  on  the  occlusal  obtain  bite. 

Chill  wax  in  cavity,  burnish  to  margins,  carve  to  conform  to  occlusion,  restore 
contour,  allowing  wax  to  extend  slightly  over  margin  of  cavity,  and  remove  model 
with  a  sharp  instrument. 

Select  a  sprue  wire  of  a  size  adapted  to  size  of  model,  being  careful  not  to  use 
one  too  large;  a  small  one  should  be  used  for  small  models. 

None  but  perfectly  clean  wax  should  be  used  and  the  wax  pattern  should  be  so 
carefully  made  and  handled,  and  the  surface  so  well  polished,  that  it  is  without  a  flaw. 

Inlays,  either  of  gold  or  acolite,  should  be  cast  as  soon  as  wax  pattern  is  made, 
while  the  wax  is  still  warm  from  the  mouth. 

Slightly  heat  point  of  sprue  wire  and  attach  it  to  wax  model,  adjusting  wire  in 
crucible-former  so  that  the  bottom  of  the  model  will  be  no  nearer  than  one-eighth  of 
an  inch  to  the  bottom  of  casting  ring,  when  the  top  of  sprue-former  is  even  with 
the  top  of  ring. 

The  investing  material  should  be  carefully  chosen.  It  must  conform  to  the 
pattern  perfectly,  so  as  to  produce  a  perfect  casting,  exactly  reproducing  the  original. 

It  should  be  an  investment  that  will  not  crack  or  check,  but  will  harden  under 
heat,  so  that  when  the  molten  metal  enters,  it  will  not  break  down  the  frail  walls 
of  investment.  An  investment  that  above  all  expands  under  heat,  taking  up  as 
much  as  possible  the  natural  shrinkage  of  metal  when  cast. 

Standard  Investment  Compound  has  been  specially  prepared  for  the  vacuum 
process  of  casting.  There  are  other  good  investments  for  other  methods,  but  none 
is  so  good  for  the  vacuum  process. 

Mix  Standard  Investment  Compound  with  tepid  water  to  consistency  of  thick 
cream  and  fill  ring. 

With  a  fine  sable  brush  (the  finer  the  better),  carefully  cover  model  and  wire 
with  the  compound,  working  carefully  into  every  angle  and  cranny  and  carefully 
blowing  the  investment  off  once  or  twice  to  prevent  bubbles  forming  next  to  wax 
model;  bubbles  fill  with  metal  when  cast,  causing  rough  casting;  failure  to  avoid 
these  bubbles,  no  matter  how  small,  will  prevent  the  fitting  of  the  inlay.  Paint  on 
enough  investment  to  cover  the  model  thoroughly,  and  then  place  crucible-former 
with  pattern  attached  on  any  fiat  surface,  pattern  upward;  then  set  ring  over 
this  with  small  end  up.  Pour  investment  in  from  one  side,  until  ring  is  filled. 
Then  take  firm  hold  of  ring  with  one  hand,  being  careful  not  to  move  it  laterally, 
and  slightly  raise  it,  to  allow  the  air  bubbles  to  escape  around  the  bottom  of  ring, 
but  do  not  jar  it  by  tai)])ing  on  the  side,  lx>cause  wax  has  an  affinity  for  air  bubbles 


INLAY  CASTING  BY  THE   VACUUM  PROCESS 


231 


suspended  in  an  investment  and  tapping  will  cause  them  to  attach  themselves  to 
the  wax  pattern  and  will  not  release.  F"or  acolite,  it  has  been  found  better  to  invest 
a  little  higher  in  ring  than  for  gold.  Fig.  1  illustrates  a  good  investment  position  for 
acolite  and  Fig.  2  for  gold. 

F'igure  1  also  illustrates  an  incorrectly  formed  crucible.  Flame  from  blowpipe 
cannot  reach  the  metal  and  it  will  not  fuse  properly.  The  form  should  be  shallow 
and  wide  as  shown  in  Fig.  2.  This  allows  the  flame  to  envelop  the  metal  and  it  will 
fuse  properly 


Fis.    1. 


Fig.  2. 


When  investment  is  set  (which,  if  properly  mixed,  takes  about  eight  minutes  in 
small  ring  and  twelve  minutes  in  large  ring),  concave  the  investment  slightly  at 
bottom  or  small  end  of  ring.  Avoid  a  smooth  surface,  as  the  air  will  not  draw  through 
a  smooth  surface  as  readily  as  a  porous  one,  and  be  sure  that  the  bottom  of  ring  is 
perfectly  clean. 

With  knife  or  small  instrument  gently  lift  out  the  crucible-former;  the  sprue 
wire  will  remain  in  the  investment;  heat  the  sprue  wire  sufficiently  over  a  Bunsen 
Burner  to  remove  it  from  investment.  In  removing  sprue  wire,  hold  ring  upside 
down,  thereby  avoiding  the  danger  of  small  particles  of  investment  failing  into 
sprue  hole.     (See  Fig.  3.) 


Fig.  ,3 


232  PRACTICAL    MANUAL   OF    DENTAL    CASTING 

Now  oil  the  bottom,  or  small  end,  of  ring  only  (with  alboline),  then  ring  is  ready 
for  heating.  Place  it,  on  its  side,  on  the  heating  stand,  over  Bunsen  Burner,  so  that 
heat  from  flame  strikes  about  the  center.  Heat  very  slowly  at  first,  as  too  rapid 
heating  generates  steam  within  the  investment,  causing  it  to  explode  and  break  away 
small  particles  of  investment,  thereby  endangering  the  casting.  As  soon  as  heat  is 
turned  on  ring,  cover  with  heat  cap  and  gradually  increase  heat,  turning  ring  around 
from  time  to  time,  until  it  has  become  a  dull  red  all  over  and  the  investment  is  also 
red  hot  through  and  through.  This  last  may  be  determined  by  holding  the  ring  with 
a  pair  of  Universal  Laboratory  Pliers  and  looking  down  into  the  sprue  hole,  where  it 
will  be  seen  that  it  is  a  dull  red  at  the  bottom.  Be  sure  the  wax  is  thoroughly  burned 
out;    a  frequent  cause  of  failure  lies  here. 

When  case  is  about  heated,  pump  up  vacuum  until  the  gauge  registers  fifteen 
inches.  See  that  seat  for  ring  is  perfectly  clean.  When  case  is  hot  place  ring  in 
position  on  bed-plate,  with  small  end  down. 

Before  fusing  the  metal  test  the  contact  of  ring  to  bed-plate,  by  turning  valve 
on  and  ofi  quickly.  If  the  contact  is  perfect,  the  indicator  will  fall  very  slowly,  if 
at  all.  When  the  contact  is  not  perfect,  it  is  usually  made  perfect  by  turning  the  ring 
on  its  base. 

If  scrap  gold  has  been  kept  free  from  platinum,  silver  and  base  metals,  it  may 
be  used  for  inlays.  It  has  the  advantage  of  retaining  its  shape  better  than  pure  gold. 
Before  using,  however,  always  melt  scrap  gold  into  a  nugget,  on  a  charcoal  block. 
Never  melt  scraps  on  the  investment  as  small  particles  may  melt  before  the  mass 
and  drop  into  sprue  entrance  and  clog  it. 

If  scrap  is  used  it  should  first  be  boiled  in  50  per  cent.  Nitric  Acid,  to  remove  any 
base  metals  that  may  be  present,  washed  and  placed  upon  a  charcoal  block  and 
melted.  While  the  mass  is  in  a  molten  condition  it  should  be  sprinkled  with  Am- 
monium Chloride  (Sal  Ammoniac).  This  should  be  repeated  until  the  gold  ripples 
like  water.  This  may  be  remelted  in  a  carbon  crucible  and  cast  into  ingots  for 
future  use  or  used  as  it  is. 

Very  little  flux  should  be  used  in  melting  gold,  as  there  is  danger  of  its  flowing 
into  the  sprue  and  closing  the  opening  into  the  mold,  preventing  a  perfect  cast,  even 
if  the  gold  goes  down  at  all.  Borax  should  never  be  used  for  a  flux.  It  has  a  ten- 
dency to  seek  the  bottom  of  the  molten  metal  and  will  cover  up  the  sprue  hole. 

A  nugget  of  sufficient  size  should  be  used  not  only  to  cast  the  inlay  but  the  sprue 
also,  and  still  have  a  sufficient  quantity  left  in  the  crucible  to  keep  air  from  entering 
the  opening.     Holes  along  the  sprue  indicate  that  too  little  metal  has  been  used. 

Fuse  metal,  if  gold,  reducing  every  particle  to  a  thoroughly  liquid  state.  Then 
turn  the  valve  and  keep  the  flame  on  the  gold  until  the  indicator  shows  a  drop  of 
five  or  six  points.  It  is  not  sufficient  merely  to  melt  the  gold.  A  very  little  Ideal 
Flux,  sprinkled  carefully  on  top  of  the  melting  mass,  will  facilitate  melting  and  flow- 
ing.    No  flux  need  be  used  in  melting  24-karat  gold. 

A  good  blowpipe  is  very  Essential,  one  that  has  perfect  combustion.  The  quicker 
the  gold  is  liquefied  while  the  investment  is  hot,  the  better  the  results  and  the  more 
perfect  the  reproduction  of  the  wax  model.  A  natural  gas  flame  is  generally  not 
hot  enough. 

It  is  extremely  liNporlaiil  that  gold  \>v  thoroughly  iuaud  and  in  perfect  condition. 

After  the  inlay  is  cast  it  should  be  washed  thoroughly  to  remove  all  investment 
attached,  then  placed  in  Hydrofluoric  Acid  which  will  remove  any  fused  silex.  The 
sprue  should  then  be  carefully  cut  off  and  the  cavity  surface  examined  minutely  for 


INLAY  CASTING  BY  THE   VACUUM  PROCESS  233 

any  small  bubbles  of  gold  that  may  be  attaelud.  If  (he  imesdneiU  is  painted  on 
very  carefully  at  first  there  will  be  little  trouble  in  this  respect. 

If  there  is  any  difificulty  in  getting  the  inlay  seated  in  the  cavit>',  an  excellent 
method  is  to  heat  the  inlay  slightly  and  apply  a  very  slight  layer  of  mercury  to  the 
surface.  This  will  unite  with  the  gold  and  upon  evaporating  away  with  increased 
heat  the  gold  will  be  left  with  a  frosted  surface.  If  the  inlay  is  now  placed  in  the 
cavity  any  point  that  may  rub  against  the  walls  will  become  burnished  and  can  be 
cut  away.  When  the  inlay  goes  to  place  perfectly,  the  surface  should  again  be  etched, 
for  the  better  adhesion  of  the  cement. 

All  inaccessible  surfaces  of  the  inlay  should  be  trimmed  and  polished  before 
setting.  However,  if  it  is  possible  to  reach  the  margin  with  a  burnisher,  it  should  be 
left  slightly  flush  to  permit  a  thorough  burnishing  before  the  cement  sets,  after  which 
the  margins  should  be  finished  and  polished  the  same  as  for  a  gold  filling. 

To  cast  Acolite  follow  directions  for  casting  gold,  except  that  it  must  be  borne 
in  mind  that  Acolite  fuses  at  a  much  lower  point  than  gold,  and  is  in  the  proper 
condition  for  casting  the  moment  it  becomes  fluidic.  Do  not  continue  playing  the 
flame  upon  the  metal  beyond  that  point.  Heat  continued  be>ond  the  fluid  point 
will  burn  and  oxydize  the  metal. 

Acolite  should  be  cast  in  molds  at  much  lower  temperature  than  gold.  After 
the  wax  has  been  burned  out,  set  the  case  off  the  fire  and  allow  it  to  cool  until  it  can 
be  comfortably  handled  with  the  naked  hand.     Then  cast. 

Place  the  ring  on  bed-plate,  drop  the  acolite  into  the  formed  crucible,  apply 
just  enough  heat  to  fuse  the  metal,  and  open  the  valve.  For  casting  acolite  the 
vacuum  should  never  be  pumped  up  higher  than  10  inches.  Faulty  margins  are 
due  to  lack  of  pressure  or  loss  of  air. 

Perfectly  clean  wax,  water,  gold  and  other  materials  must  be  used. 

Investments  must  be  properly  mixed  and  applied. 

The  wax  must  be  thoroughly  burned  out. 

Aerdentalloy,  Aluminum  and  Acolite  must  not  be  overheated. 

A  sprue  wire  adapted  to  the  size  of  model  must  be  used. 

The  investing  material  must  be  adapted  to  the  vacuum  process. 

More  metal  than  is  required  for  the  case  must  be  used.  If  holes  appear  in 
casting  near  or  alongside  the  sprue,  more  gold  m^ist  be  used;  or  add  2^(,  platinum 
wire  rolled  thin,  and  fed  into  the  boiling  gold. 

Good  clean  gold  in  nugget  form  must  be  used  and  thoroughly  fused. 

Cases  must  be  promptly  cast  after  the  investment  has  set. 

If  inlays  come  out  black  and  rough,  case  has  not  been  sufificiently  heated.  Get 
it  hot  through  and  through,  so  that  a  dull  red  spot  can  be  seen  when  lookingintothe 
sprue  hole.  Carbon  deposit  left  by  wax  must  be  burned  out.  Dark  spots  are 
caused  by  gases  given  off  by  combustion  of  wax.  If  burned  out  clean  before  casting, 
the  inlay  will  be  clean. 


REINFORCING  PRINCIPLE  OF  MESH  IN  WAX  PATTERN  WORK 

By  A.  W.  Tatham,  D.D.S.,  Detroit,  Mich. 

Detailed  description  of  any  particular  form  of  crown  is  properly  preceded  by 
a  few  general  considerations  relative  to  this  subject,  so  rapidly  gaining  in  the  attention 
of  our  profession  generally.  The  principle  of  reinforcing  wax  patterns  for  castings 
is  applied  most  practically  to  root  bases  for  any  form  of  crown,  whether  it  is  anterior 
all-porcelain  with  inlay  setting  or  a  posterior  bicuspid  or  molar  used  either  as  a 
single  restoration  or  abutment  for  bridge.  Some  forms  of  crowns  lend  themselves 
more  easily  than  others  to  this  method.  Let  us  consider  first  the  anterior  inlay 
setting.  A  perfectly  non-impinging  coping  is,  beyond  all  dispute,  the  thing  to  be 
attained,  and  may  be  by  the  following  technique: 

Prepare  the  root  end,  making  a  well-defined  bevel,  and  upon  the  root  place  a 
small  strip  of  mesh — push  pin  through  and  trim  to  approximately  the  proper  size 
of  mesh  to  be  used. 


Now  remove  and  run  some  hot  wax  upon  the  upper  side  of  mesh,  replace  upon 
the  root,  and  with  a  piece  of  soft  red  rubber  such  as  is  used  for  pencil  eraser,  force 
mesh  and  wax  down  upon  the  root.  Special  emphasis  is  laid  here  upon  the  use  of 
the  rubber,  because  nothing  else  will  so  easily  and  surely  enable  you  to  force  the 
waxed  mesh  well  home  and  slightly  over  the  edges. 

Take  this  pattern  off,  turning  the  inside  upward,  and  you  may  find  that  a  little 
more  wax  is  required.  If  so,  run  in  just  a  surface,  or,  with  a  hot  round  burnisher, 
remelt  the  whole  inside.  While  this  is  warm,  re-adapt  thoroughly  to  the  root, 
using  rubber  again.  The  slight  margins  may  now  be  very  easily  and  accurately 
brought  to  place  by  the  use  of  a  slightly  warm  flat  burnisher.  Trim  this  pattern, 
as  you  would  a  band,  to  suit  the  case  in  hand.  Toward  the  labial  side  nearly  all  of 
the  coping  may  be  trimmed  off  for  esthetic  reasons.  Replace  the  pattern  as  many 
times  as  is  necessary  to  bring  margins  to  place.  To  warm  the  pattern  for  these 
re  adaptations,  drop  it  into  warm  water,  or  move  it  to  and  fro  over  a  flame  until 
uniformly  warmed  through. 

The  next  step  is  to  place  the  crown  upon  the  top  of  the  root  base  pattern,  and 
this  is  easily  accomplished  by  warming  the  upper  portion  of  the  pattern  while  it  is 
on  the  root,  with  a  hot  air  chip  blower.  If  wax  is  insut!:cient,  run  a  little  more  over 
the  surface.  The  tooth  should  be  slightly  warmed  to  prevent  too  sudden  chilling 
of  the  wax.     Thus  it  is  readily  seen  a  very  thin  wax  impression,  with  a  slightly 


REINFORCIXG  PRIXCIPLE  OF  MESH  EX  WAX  PA  TTERX  WORK     2:i.-, 

turnover  edge  for  coping,  may  be  manipulated  with  surprising  ease  and  accuracy 
This  coping  will  fit  when  cast  and  give  uniform  results. 

The  foregoing  technique  is  employed  where  a  pronounced  band  or  margin  is 
required.  The  following  technique  will  be  found  ven.-  efficient  where  no  extensive 
margin  or  turnover  edge  is  essential. 

Another  technique  especially  useful  for  all  anterior  teeth  where  only  a  thin  joint 
is  required  is  to  trim  the  mesh  tooth-wise,  press  a  piece  of  mesh  with  thumb  upon  the 
tooth,  prick  hole  for  head  of  pin,  push  pin  with  flange  into  tooth,  having  flange  this 
side  of  mesh,  tack  with  a  little  warm  wax  and  trim  the  mesh  around  the  crown 
properly. 

The  next  step  is  to  run  enough  hot  wax  around  pin  and  pattern  and  j'ou  arc 
ready  to  press  crown  and  pattern  upon  the  root. 


In  this  technique  the  method  is  simple  and  positive,  the  mesh  acting  as  a  guide 
for  extreme  thinness  of  anterior  part  of  pattern  and  prevents  all  spreading  and 
splitting  of  pattern. 

Note — Hollow  sprues  are  ver\"  advantageous  in  root  base  patterns. 

It  must  be  quite  apparent  to  anyone  having  made  these  patterns,  without 
reinforcement,  the  number  of  difficulties  encountered.  One  of  the  most  annoying 
troubles  in  forcing  down  this  pattern  is  the  splitting  or  spreading  of  the  wa.x — to  say 
nothing  of  the  lack  of  slight  turnover,  which  is  wholly  absent  or  inaccurate.  This, 
to  my  mind,  is  one  of  the  most  important  uses  of  the  mesh,  as  the  forming  of  an  ac- 
curate and  esthetic  adjustment  of  the  anterior  porcelain  crown  ever>-  operator  is 
compelled  to  face.  This  operation  is  rendered  practical  and  easy  by  the  aid  of  the 
mesh. 

CROWN"    BRIDGE    .\BUT.MEXT 

Let  us  consider  a  t>pe  of  crown  for  crown  bridge  abutment.  The  waxed  mesh 
base  is  practically  the  same  as  for  the  base  described  above,  except  that  the  pin  is 
bent  over  at  a  right  angle  or  a  thin  disc  cf  gold  or  silver  tacked  to  pin,  with  solder 
mesh  ahvays  placed  upper  side  of  disc,  making  removal  of  pattern  ea.s>- — also  that 
some  roots  rccjuirc  a  definite  band.      Make  this  band  hy  extending  the  \\axcd   mesh 


236 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


and  trim  as  you  would  in  forming  a  metal  band.  Note  at  this  point  a  most  impor- 
tant feature  of  gold  mesh,  i.  e.,  it  does  not  buckle;  it  is  woven,  therefore  pliable, 
giving  in  all  directions,  and  may  be  placed  upon  the  root  and  extended  some  dis- 
tance as  a  band  without  the  annoyances  encountered  in  continuous  metal. 

Select  a  tooth  of  the  Goslee  type,  or  Steele's  Facing,  all-porcelain  type,  since 
these  give  the  Y-shape  slant  or  space  necessary  for  adjustment  and  surface  for 
soldering  the  dummy  teeth  in  for  bridgework.  Here  is  a  means  for  adjusting  the 
tooth  directly  in  the  mouth  in  most  cases  without  casting  the  root  base  separately — 
eliminating  running  of  models,  etc.     The  mesh  is  placed  upon  the  tooth,  hot  wax 


run  upon  the  mesh;  pressed  to  place  quickly;  taken  ofif  the  tooth;  re-trimmed  and 
re-adapted  in  the  same  manner  as  a  root  base  impression.  These  two  patterns  are 
now  ready  to  be  attached.  The  point  is  that  the  mesh  upon  the  tooth,  the  tip  end 
for  attaching,  may  be  heated  and  attached  at  any  angle  or  removed  as  often  as  is 
necessary,  and  when  finally  articulated,  the  porcelain  tooth,  by  reason  of  the  mesh 
reinforcing  pattern,  may  be  easily  taken  from  the  pattern  without  distortion. 

Furthermore,  the  mesh-wax  patterns  are  unlike  those  with  a  continuous  metal 
backing,  because  they  can  be  re-shaped  or  changed  readily.  The  enmeshing  qualities, 
ever  present  in  adjustment,  render  it  possible  to  achieve  through  casting,  truly 
splendid  results.  Only  men  who  will  not  see  or  who  prefer  the  old  way,  just  because 
it  is  old,  fail  to  see  in  this  progressive  method  that  which  gives  to  casting  its  most 
desirable  feature.  The  molar  crown  can  be  just  as  easily  manipulated  as  a  bicuspid. 
In  the  process  of  adjustment  it  may  become  necessary,  in  articulating  a  bicuspid. 


to  place  a  warm  little  ball  of  beeswax  for  a  cushion  while  obtaining  adjustment. 
This  ball  need  not  be  taken  out,  but  finished  right  over  with  the  inlay  wax.  The 
beeswax  cushion,  remaining  soft  a  long  time,  facilitates  articulation,  which  otherwise 
would  be  dilificult  of  accomplishment. 

Should  it  become  necessary  to  cast  the  base  separately  and  then  take  an  im- 
pression and  run  models,  an  accurate  pattern  for  base  and  crown  can  be  easily  formed 
in  a  short  time,  and  the  two  patterns  can  be  cast  in  the  same  mold.  The  two  castings 
may  then  be  waxed  in  place  upon  the  articulation  and  soldered  together.  Care  must 
be  taken  to  make  the  root  base  pattern  very  thin.  There  is  to  be  noted  here  a  very 
important  point  in  favor  of  the  mesh.  A  hot  spatula  may  be  run  over,  where  pat- 
tern   is  in   position  on  root,  taking  off  the  wax  or  shaping  right  down  to  the  mesh 


REINFORCING  PRINCIPLE  OF  MESH  IN  WAX  PA  TIERN  WORK       2:37 

il.sclf,  and  ihe  impression  on  the  under  side  will  remain  unharmed.  This  palLern  is 
left  \er>  thin  so  that  there  will  be  room  for  adjusting  the  tooth  coping  to  the  root 
base  coping  when  they  are  set  upon  the  articulator  for  articulation.  It  is  assumed 
that  a  tooth  will  be  selected  and  approximately  fitted  before  attempting  to  form 
any  pattern. 

Much  might  be  said  concerning  the  modifications  of  these  two  types,  but  believe 
that  the  anterior  all-porcelain  type  for  anterior  and  the  saddle  shape  all-porcelain 
typefor  bridge  abutments  are  the  most  generally  used,  being  esthetic  and  economical. 
The  selection  of  teeth  for  bridge  abutments  and  dummies  for  bridgework  would  be 
seriously  hampered  for  casting  without  a  proper  facing  type  of  tooth  suited  to  wax 
pattern  work.  The  usual  type  of  fixed  pin  facing  tooth  is  not  very  satisfactory  for 
casting.  The  new  Dimelow  facing  presents  a  form  of  facing  that  is  best  suited  to 
wax  pattern  work.  The  staple  pins  draw  with  the  wax  mesh  pattern,  giving  a 
re]jlaceable  facing      The  staple  pins  enter  into  the  holes  of  porcelain  facing  at  an 


angle,  giving  strength  and  permitting  the  tipping  of  the  cutting  edge  of  the  facing. 
This  facing  has  a  distinct  advantage  in  short  bite  and  forming  of  wax  mesh  dummies. 
It  will  be  readily  seen  that  the  reinforcing  principle  may  be  applied  to  any  form 
of  root  of  any  size,  in  any  position,  anterior  or  posterior — without  having  always  to 
change  technique  or  to  encounter  other  difificulties. 

ALLOYED  EDGES 
It  is  quite  well  established  that  pure  gold,  properly  treated,  casts  best.  For  a 
thin  margin  or  band,  the  one  objection  to  pure  gold  is  that,  being  soft,  it  lacks  the 
proper  tenacity  for  polishing  and  burnishing  to  advantage.  The  mesh  is  22k,  and 
when  the  pure  gold  is  cast  into  it  the  edges  or  margins  become  an  allo>",  giving  the 
pure  gold  just  the  required  quality  for  this  part  of  the  casting.  Thus,  one  ma\-  cast 
with  pure  gold  and  while  in  the  mold  form  an  alloy  where  it  is  most  needed. 

CERVICAL    TWO-THIRDS 

There  are  very  few  operators  who  are  not  willing  to  admit  thai  the  approximai 
space  at  this  point  offers  some  difficulties  and  inaccuracies  in  forming  the  wax 
pattern.  The  application  of  reinforcing  the  wax  pattern  at  this  [wint  is  so  simple 
and  eflectivc  that  only  a  brief  description  of  the  technique  is  recjuired.     Manii>uiate 


238 


PRACTICAL  MANUAL  OF  DENTAL  CASTING 


between  teeth  as  you  would  a  piece  of  silk  tape;  enter  the  mesh  into  the  pattern  with 
warm,  thin  spatula;  remove,  trim  surplus  mesh,  leaving  margin;  over  this  flow  a 
little  wax;  return  to  cavity  and  burnish  margin  with  warm  spatula.  By  this 
principle  you  are  always  certain  that  the  cervical  two-thirds  is  correct. 

Just  a  word  in  regard  to  compound  inlays  or  shallow  wax  inlay  patterns.  These 
patterns  often  become  distorted  in  drawing,  and  is  not  noticed  until  too  late.  Many 
times  the  adding  of  wax  to  an  edge  or  margin  of  these  types  of  inlays  is  quite  difficult. 
When  the  general  reinforcement  or  framework  of  mesh  is  employed,  these  difficulties 
are  obviated.     Technique  is  similar  to  root  base.     Another  feature  of  no  minor 


importance  is  the  "'Mesh  Bite  Crown."  A  band  is  made  and  adjusted  in  the  usual 
way.  Attach  a  mesh  cover  at  top  of  the  band.  Tack  mesh  with  solder  at  two 
points.  A  slight  amount  of  wax  is  placed  in  the  mesh  and  a  bite  is  taken.  Easy 
and  accurate  adjustment  is  quickly  made,  requiring  no  carving  inside  and  taking  a 
minimum  amount  of  gold  for  occlusion.  The  crown  is  cast.  The  outer  edges  of 
the  mesh  prevent  the  edges  of  the  occlusion  from  shrinking  in  over  the  band.  Union 
is  perfect. 

In  the  case  of  the  gold  crown,  where  the  bite  is  very  short  and  the  crown  part  of 
tooth  is  gone,  generally  requiring  a  solid  construction,  and  where  a  porcelain  crown 
cannot  be  used — make  band  in  usual  way;  cap  with  mesh.     Insert  pins  through  mesh 


into  root  channel.  The  bite  is  now  taken  and  crown  is  ready  for  casting.  This 
gives  a  strong  attachment  since  the  casting  usually  has  at  least  two  pins,  and  these 
may  be  tied  together  by  placing  a  small  amount  of  wax  between  the  pins  close  up  to 
the  top  on  the  under  side.  In  the  casting,  gold  takes  the  place  of  the  wax  and  makes 
a  very  strong  connection  of  the  pins  to  the  crown. 

CONTROL    OK    SHRINKAGE    AND    WARPAGE 

How,  it  is  often  asked,  can  the  mesh  exert  any  restraining  power  over  the  cooling 
metal?  Let  the  most  conservative  but  impartial  operator  make  a  reasonable 
number  of  tests,  casting  both  with  and  without  the  mesh,  taking  the  same  care  that 
he  docs  in  his  ordinary  practice  in  casting,  and  he  will  find  results  more  uniform  with 


REINFORCING  PRINCIPLE  OF  MESH  IN  WAX  PA  TTERN  WORK       239 

mesh  than  without.  Without  mesh,  under  ideal  conditions,  with  a  perfect  tech- 
nique, and  the  expenditure  of  much  time,  observing  carefully  all  the  details  of 
casting,  one  can  obtain  good  results.  Now,  the  majority  of  busy  practitioners  who 
are  doing  casting,  appreciate  some  of  the  difficulties,  especially  in  root  base  work, 
when  they  get  down  to  every-day  practice  and  have  an  open  mind  and  a  welcome  for 
a  simple  and  scientific  principle  that  lightens,  expedites  and  assures  good  results. 

Here  is  the  result  of  a  test  made: 

A  wax  pattern  with  several  thicknesses  of  mesh,  also  one  without  mesh,  were  cast 
at  the  same  time,  under  the  same  and  very  favorable  conditions,  and  submitted  for 
analysis  to  an  expert.     It  was  found  that  the  specific  gravity  of  the  casting  containing 


the  mesh  was  considerably  less  than  that  without  mesh,  indicating  that  the  interstices 
contained  air,  and  which  would  have  a  tendency  to  throw  the  contraction  from  the 
surface  which  the  mesh  immediately  underlies.  Another  theory  is  that  the  casting 
cools  quickest  around  the  mesh,  inasmuch  as  tests  have  proven  that  the  mesh  does 
not  melt  upon  being  surrounded  by  the  molten  gold,  and  which  would  have  a  tend- 
ency to  minimize  the  contraction  in  the  surface  which  the  mesh  immediately  under- 
lies— the  adaptation  surface. 

Exhaustive  tests  have  also  proven  that  the  mesh  does  not  hamper  the  casting. 
Care,  however,  should  be  taken  to  bring  the  gold  to  liquid  state.  Use  equivalent 
to  ten  pounds'  pressure. 

Note.     A  certain  amount  of  change  of  shape  of  wax  paltern  is  due  to  the  wax.     The  mesh 
acts  as  a  stiffener  and  prevents  this  trouble. 


COMBINATION  FILLINGS  OF  CAST  GOLD  AND  PORCELAIN  OR 
SILICATE  CEMENTS 

By  Dr.  C.  H.  Neill,  Fairmont,  W.  Va. 

This  is  a  method  of  using  cast  gold  inlaws  in  conjunction  with  hnv-fusing  porce- 
lain and  silicate  cements. 

In  the  large  approximal  inciscjr  cavities  in  the  anterior  teeth,  to  replace  the 
ordinary  contoured  filling  or  contoured  inhu',  I  prepare  the  wax  model  in  the  usual 
manner  and  remove  the  labial  aspect  of  it;  prepare  in  the  labial  aspect  a  box-shaped 
cavity,  cast  inlay,  cement  into  position,  and  start  a  new  operation  on  the  labial 
cavity  prepared  in  the  inlay.  That  gives  us  the  same  strength  of  a  gold  inlay  without 
the  labial  aspect  of  gold.  If  artificial  enamel  is  used  the  incisal  edges  can  be  well 
protected.  If  low-fusing  porcelain  is  u.sed  as  a  veneer  there  need  be  no  gold  showing 
at  all. 


THE  TECHNIQUE  OF  CASTING 

USING  STEELE'S  INTERCHANGEABLE  TEETH  AND  BACKINGS 
By  Dr.  C.  E.  Talbert,  Columbus,  Ohio. 

I  shall  not  advance  any  theories  or  suppositions  in  the  paper  which  follows,  but 
will  give  merely  a  plain  statement  of  facts  which  have  been  proven  by  several  years 
of  experiment  and  daily  practice. 

The  technique  of  casting  a  crown  or  bridge,  using  Steele's  interchangeable 
teeth  and  backings,  is  practically  the  same,  up  to  the  point  of  investing,  as  that  of  a 
crown  or  bridge  that  is  to  be  completed  by  soldering,  the  only  difference  being  that 
the  backings  and  other  parts  to  be  cast  upon  must  he  fluxed  in  the  manner  as  heroin- 
after  described,  and  that  the  waxing  must  be  more  carefully  done  and  the  piece 
carved  just  as  it  is  desired  to  have  it  when  finished. 

Let  us  take,  for  example,  an  incisor  Richmond.  You  are  supposed  to  have  the 
coping  and  pin  in  place,  either  in  the  mouth  or  upon  a  model.     It  is  imperative  that 


Fig.  1 

the  pin  be  either  of  platinum  or  iridio-platinum,  as  a  base  metal,  such  as  platinoid, 
will  often  become  disintegrated  and  weakened.  Select  the  proper  tooth  and  grind 
to  place,  preserving  the  bevel  of  the  ridge-lap,  or  increasing  it  a  little  if  necessary, 
so  that  when  the  grinding  is  completed  it  will  touch  the  coping  at  its  extreme  labio- 
cervical  point  only,  leaving  a  V-shaped  space  between  the  two.  Now  place  the  tooth 
upon  the  backing  and  trim  the  latter  to  the  tooth,  closely  on  the  sides,  but  leaving 
it  a  little  longer  than  the  tooth  at  the  incisal  edge.  Next  grind  the  ridge-lap  end  of 
the  backing  to  the  tooth,  giving  it  the  same  bevel.  Remove  the  backing  and, 
grasping  it  with  a  pair  of  soldering  pliers,  hold  it  so  that  the  beveled  end  will  be  level, 
and  place  a  tiny  speck  of  20k  solder  on  the  corner  of  the  backing  farthest  from  you, 
as  in  Fig.  1.  Hold  in  the  flame  until  the  solder  sweats  down,  but  remove  before  it 
flows.  Next  take  a  piece  of  34-gauge  pure  gold  or  a  piece  of  platinum  foil  slightly 
wider  than  the  backing  and  long  enough  to  balance  on  the  end  thereof,  with  enough 
material  projecting  over  the  ridge-lap  to  cover  the  end  of  the  tooth  when  the  latter 
is  in  place  (Fig.  2).  Have  this  piece  perfectly  flat  so  that  when  it  is  laid  upon  the 
end  of  the  backing  it  will  have  a  three-point  contact,  viz:  the  little  globule  of  solder, 
the  opposite  corner  of  the  backing,  and  the  end  of  the  post.  Carry  carefully  to  the 
flame  and  hold  steadily  until  a  slight  movement  of  the  piece  indicates  that  the  solder 
has  flowed  and  the  piece  settled  to  place.  Now  put  the  tooth  on  the  backing  and 
be  sure  that  it  goes  easily  to  place  without  forcing,  not  only  at  this  time  but  after  all 
subsequent  operations  of  soldering  or  casting.  If  there  is  found  to  be  any  obstruc- 
tion, remove  it  carefully  before  proceeding  further.     Now  trim  around  the  cervical 


THE  TECHNIQUE  OF  CASTING 


:ii 


edge,  but  leave  that  portion  of  the  Hap  that  ovi'Haijs  the  l)aekiiig,  which  is  to  l)e 
burnished  down  closely,  as  is  also  that  part  which  covers  the  end  of  the  tooth  (Pig.  '^). 
Drop  the  piece,  while  hot,  in  pickle  and  leave  for  a  few  minutes.  It  will  then  be 
ready  for  the  flux.  The  flux  to  be  used — and  it  is  the  only  one  that  can  be  used 
successfully — is  a  saturated  solution  of  boracic  acid  in  grain  alcohol.  This  is  also  a 
most  satisfactory  flux  for  all  small  soldering  operations. 

To  prepare  a  stock  solution,  fill  a  bottle  about  one-fourth  full  of  boracic  acid  and 
fill  up  with  alcohol,  shake  a  few  minutes  and  allow  to  settle,  using  only  the  clear 


Fig.  2 


liquid.  If  you  have  a  considerable  excess  of  the  powder,  the  stock  can  be  kept  up 
by  occasionally  refilling  with  alcohol.  The  best  way  to  apply  the  flux  is  from  an 
office  preparation  bottle  with  a  small  camel's  hair  brush,  or  the  piece  can  be  dipped 
bodily  into  it. 

Take  the  piece  to  be  fluxed  in  a  pair  of  soldering  pliers  and  apply  the  solution. 
Ignite  the  alcohol  from  the  flame  and  allow  it  to  burn  ofT.  Then  hold  the  piece  in 
the  flame  a  moment — until  you  see  the  deposit  fuse,  but  do  not  allow  it  to  approach 
a  red  heat.  Allow  it  to  cool  spontaneously  and  you  will  find  the  surface  uniformly 
covered  with  a  thin  film  of  flux  that  can  be  handled  without  displacement  and  which. 


Mg.  -i 


in  the  subsequent  operation  of  casting,  will  absolutely  prevent  oxidization  of  the 
surface  to  be  cast  upon.  No  care  need  be  taken  to  keep  the  flux  from  the  face  of 
the  backing,  nor  is  any  antiflux  or  other  stop-out  necessary,  as  in  the  case  of  a 
soldered  piece,  as  the  investment  used,  if  properly  applied,  answers  ever>'  purpose. 
We  are  now  ready  to  proceed  with  waxing  up  the  case.  Unlike  the  casting  of 
inlays,  the  wax  to  be  used  is  of  little  importance  except  as  regards  its  tenacity  in 
holding  the  parts  together  and  the  facility  with  which  it  may  be  carxed.  A  good, 
sticky- wax  is  best  to  unite  the  parts  so  that  they  may  be  removed  from  the  mouth  or 
the  model.  The  operation  may  then  be  completed  with  pink  baseplate  wax.  wiiich 
carves  very  nicelv,  or  with  anv  of  the  casting  waxes  on  the  market.     Flow  on  enouuh 


242  PRACTICAL  MANUAL  OF  DENTAL   CASTING 

wax  to  give  the  desired  contour  and  build  the  incisal  edge  to  a  thickness  about  equal 
to  No.  20-gauge  plate.  Trim  the  wax  flush  with  the  end  of  the  backing,  which,  as 
previously  mentioned,  must  be  slightly  longer  than  the  tooth.  This  is  with  the 
object  of  protecting  the  porcelain  when  the  piece  has  been  finished  and  finally 
mounted,  which  object  may  be  still  farther  advanced  by  grinding  the  porcelain 
very  thin,  thus  precluding  the  possibility  of  contact  with  the  occluding  tooth.  After 
grinding,  the  porcelain  may  be  repolished  with  gloss  sticks  or  other  polishing  material. 

Of  course,  the  entire  Richmond  or  bridge  dummy,  including  the  backing  and 
post,  may  be  cast  in  one  piece  if  desired,  in  which  case  the  method  of  procedure  would 
be  first  to  grind  the  tooth  into  place,  either  in  the  mouth  or  on  the  model,  and  then 
remove  and  cither  thoroughly  wet  or  oil  the  slot  and  back  of  the  tooth.  Then  flow 
on,  to  the  proper  thickness,  some  good  casting  wax,  being  sure  to  have  the  slot  well 
hiled.  After  chilling  it  may  be  waxed  to  place,  carved  as  desired,  the  tooth  removed 
and  the  case  proceeded  with  as  hereafter  described.  There  are  some  serious  objec- 
tions to  this  method,  however,  the  chief  of  which  are,  first,  the  difficulty  of  removing 
and  replacing  the  tooth  without  distorting  the  post  or  backing,  and  the  fact  that 
after  casting  the  post  will  fit  the  slot  so  closely  as  to  preclude  proper  cementation 
when  the  case  is  completed.  Furthermore,  no  matter  how  carefully  the  piece  may  be 
invested,  there  is  almost  certain  to  be  some  minute  globules  of  gold  cast  along  the 
post  or  upon  the  ridge-lap  or  backing,  which  would  cause  considerable  trouble  in 
removing. 

Some  of  these  objections  may  be  removed  by  using  the  posts  for  casting  which 
are  supplied  by  the  manufacturers,  but  the  danger  still  remains  that  the  post  may  be 
gotten  out  of  alignment  or  otherwise  displaced  or  the  backing  distorted.  In  view  of 
these  considerations,  I  strongly  recommend  the  use  of  the  backings,  as  supplied  by 
the  makers,  in  the  manner  already  described. 

The  investment  of  the  piece  is  next  in  order,  and  the  investment  material,  next 
to  the  f.iix,  is  of  the  utmost  importance.  I  shall  not  enter  upon  a  discussion  of  the 
qualities  necessary  to  a  good  investment,  but  will  give  you  the  formula  for,  and  the 
method  of  preparing,  that  which  I  have  selected  as  the  best,  after  several  years' 
trial  of  most  of  those  now  offered  by  the  dealers.  It  is  composed  of  four  parts  by 
weight  of  finely  powdered  silex  and  one  part  of  French's  in- pression  plaster.  These 
ingredients  must  be  thoroughly  mixed  by  repeated  siftings.  I  sift  them  twenty  to 
thirty  times  through  a  fine  sieve  and  make  up  enough  at  one  time  to  last  several 
months,  as  the  longer  the  mixture  is  kept  the  better  it  is,  provided  it  is  stored  in  a 
dry,  warm  place  in  isooden  boxes,  the  wood  tending  to  absorb  any  slight  moisture  it 
may  contain.  Too  much  importance  cannot  be  attached  to  the  mixing  and  curing 
of  this  investment  material. 

The  operation  of  investing  the  piece  is  practically  the  same  as  that  of  investing 
an  inlay.  Place  the  sprue  wire  so  that  it  points  directly  into  the  V-shaped  space 
between  the  ridge-lap  apron  and  the  coping,  and  mount  the  piece  on  the  crucible- 
former.  Mix  a  tolerably  thick  batter  of  investment  and  paint  it  onto  the  piece  with 
a  very  small  stiff  brush,  working  it  well  under  the  backing  post  and  very  carefully 
excluding  even  the  minutest  air  bubbles.  After  the  piece  is  well  covered,  place  the 
casting  ring  on  the  base  and  proceed  to  pour  the  balance  of  the  mix,  being  careful 
to  add  but  little  at  a  time,  and  working  it  down  around  the  sides  of  the  flask  with  a 
small  cement  spatula,  and  by  holding  the  flask  firmly  down  and  tapping  the  sides 
with  the  spatula  handle. 

The  correct  proportions  of  in\es1ment  material  and  water  for  a  pro[)cr  mix,  as 


THE  TECHNIQUE  OF  CASTING 


243 


well  as  a  sufficient  amount  to  fill  the  ordinary  inlay  flask,  are  12  dwts.  of  investment 
and  two  teaspoonfuls  of  water.  You  double  this  quantity  for  a  larger  flask.  Procure 
a  small  tin  ointment  box,  and  after  weighing  this  amount  shake  it  well  down  level 
and  trim  the  box  to  the  level  of  the  material;  you  will  then  have  a  correct  measure 
for  all  subsequent  mixes. 

When  the  investment  is  set,  which  will  be  in  about  eight  minutes,  warm  and 
remove  the  crucible-former.  Grasp  the  sprue  wire  with  a  pair  of  hot  pliers,  holding 
it  so  for  a  few  minutes  that  the  heat  may  be  transmitted  to  the  wire,  when  it  may  be 
easily  withdrawn.  Place  the  flask  on  its  side  on  an  inclined  rack,  about  two  inches 
above  the  opening  of  a  Bunsen  burner,  with  the  sprue  opening  at  the  lowest  point — 
that  the  melting  wax  may  to  a  certain  extent  drain  out.  Have  the  flame  turned  as 
low  as  possible.  It  should  not  be  more  than  half  an  inch  high,  as  shown  in  Fig.  4. 
Keep  at  this  point  for  twenty-five  minutes,  at  the  end  of  which  time  turn  it  up  to 


Fig.  4 


Fig.  5 


about  an  inch  (Fig.  5).  .\l  the  end  (jf  fi^•e  minutes  more  turn  up  until  the  flame 
barely  touches  the  flask  (Fig.  6),  and  after  another  five  minutes  turn  on  the  full 
flame  (Fig.  7).  After  five  minutes  more  it  is  ready  for  the  cast.  To  summarize: 
Twenty-five  minutes  for  the  first  heat,  five  minutes  for  the  second,  five  minutes  for 
the  third,  and  five  minutes  for  the  fourth — forty  minutes  all  told.  Have  the  air  and 
gas  so  regulated  in  the  burner  that  it  will  burn  with  a  slightly  yellow  flame  rather 
than  a  noisy  blue  one.  The  flame  during  the  last  heat  will  then  lap  entirely  around 
the  flask  instead  of  splitting  off  at  the  sides.  At  the  end  of  the  time  allotted  for 
the  heating  the  flask  should  show  slightly  red,  but  the  investment  not  at  all,  and  it 
must  be  removed  from  the  fire  and  the  cast  made  without  allowing  it  to  cool  longer 
than  is  necessary-  while  preparing  to  melt  the  gold. 

The  gold  to  be  used  in  casting  must  necessarily  be  of  considerable  lower  karat 
than  that  which  it  is  to  be  cast  upon.  It  has  generally  been  conceded  that  the  solder 
sold  for  use  with  ISk  plate  is  good  enough  for  a  soldered  bridge.  At  any  rate,  it  is 
the  highest  karat  that  can  be  safely  used  in  casting  upon  20k  gold  or  platinum  allo>- 
backings.  If  you  wish  to  use  a  finer  gold  you  must  have  pure  gold  or  pure  platinum 
backings.  Before  fusing  the  solder  for  making  the  cast  it  must  first  be  melted  into 
a  nugget  upon  a  charcoal  block,  using  plenty  of  borax  and  app!>ing  only  just  sufticient 


244  PRACTICAL  MANUAL  OF  DENTAL  CASTING 

heat  to  accomplish  the  purpose.  Do  not  attempt  to  use  less  than  four  dwts.  of 
solder  for  casting  a  Richmond,  and  more  in  the  same  proportion  for  a  bridge,  as  it  is 
important  to  have  plenty  of  excess.  Note  carefully  the  sluggish  action  of  the  solder 
under  the  blow-pipe  so  that  you  may  be  able  to  judge  when  fusing  for  the  cast  just 
when  the  fusion  is  complete,  as  it  will  not  dance  and  boil  as  a  higher  grade  of  gold 
usually  does.  Also  after  casting,  the  pressure  must  be  sustained  a  little  longer 
than  is  necessary  when  using  a  higher  grade  of  gold. 

The  technique  of  casting  a  bridge  does  not  differ  materially  from  that  of  a  crown, 
except  that  provision  must  be  made  for  easily  removing  it  from  the  model  and  a 
greater  number  of  feeders  supplied. 

Before  pouring  the  impression  any  shell  crown  must  be  partly  filled  with  wax 
and  the  posts  of  Richmond  crowns  partly  covered  so  that  by  slightly  warming  they 
may  be  readily  removed  and  replaced  after  cleaning.  The  model  must  then  be 
slightly  oiled  between  the  abutments  with  liquid  vaseline  or  other  oil,  and  the  case 
proceeded  with  as  in  case  of  a  soldered  bridge.  This,  however,  is  one  of  the  methods 
often  used  in  soldered  work. 

After  the  case  is  waxed  and  carved  as  it  is  desired  to  have  it  reproduced,  there 
is  nothing  more  to  do  but  to  fix  the  sprues  and  proceed  to  invest  the  cast. 

The  feeders  must  be  at  least  three  in  number — one  wire  placed  about  the  center 
and  two  feeders  formed  by  little  rolls  of  wax,  one  at  either  end  of  the  bridge  converg- 
ing to  the  free  end  of  the  wire  and  waxed  to  it  with  a  hot  spatula.  It  may  now  be 
mounted  upon  the  base  or  crucible-former  and  proceeded  with  as  previously 
described. 

In  conclusion,  I  will  recapitulate  the  more  important  considerations: 

First — The  method  of  fluxing,  which  has  not  to  my  knowledge  been  published 
before,  is  absolutely  essential  to  a  perfect  union  between  the  metal  cast  and  the  metal 
cast  upon  and  will  invariably  produce  that  result. 

Second — The  investment  must  be  one  that  will  not  shrink  or  check  and  one  that 
will  spread  with  a  brush  like  paint  and  fill  in  smoothly  without  bubbles. 

Third — The  case  must  not  be  overheated — the  merest  approach  to  redness  of 
the  flask  is  permissible,  but  the  gold  within  must  not  reach  the  red  heat.  This  result 
will  be  closely  approximated  by  following  the  formula  for  heating  as  given,  but  by 
experiment  may  be  changed  to  suit  any  slight  difference  in  the  burner  used. 

Fourth — If  solder  is  used  in  casting  much  caution  must  be  used  not  to  overheat 
in  fusing,  but  be  sure  it  is  fused  and  cast  as  soon  as  you  are  certain  that  it  is. 

If  these  four  essential  features  are  carefully  observed  there  will  be  few,  if  any, 
failures. 


HOLDING  INLAYS  WHILE  POLISHING 

By  Dr.  G.  B.  Speer,  Los  Angeles,  Cal. 

In  the  February  number  of  the  Summary,  Dr.  R.  C.  Brophv,  of  Chicago,  gave 
a  description  of  Dr.  Moore's  vise  for  holding  inlays  while  polishing.  My  way  is  as 
follows: 

Take  a  pair  of  Dr.  W.  Van  Hook's  (or  other  make)  mouse  tooth  hemostatic 
forceps,  which  can  be  gotten  at  any  surgical  supply  house  for  $1.25.  Snap  them  on 
the  inlay  and  you  can  hold  it  in  any  shape  desired.  Also,  let  your  assistant  turn  a 
stream  of  cold  air  on  the  inlay  while  grinding  and  it  remains  cool.  The  assistant 
and  cold  air  have  been  a  great  help  to  me  at  the  chair  by  keeping  the  bur  cool  while 
cleaning  out  cavities. 

And  while  you  are  buying  your  hemostatic,  also  buy  a  five-pound  can  of  sur- 
geon's green  soap  and  use  same  for  moistening  felt  and  brush  wheels  in  polishing 
plates.  The  remainder  may  be  used  for  washing  the  hands.  Once  you  have  used 
this  soap  you  will  never  go  back  to  any  other.  It  is  not  only  cheaper,  but  cleanses 
and  softens  the  hands  much  better. 

How  I  make  a  sprue  wire  for  holding  and  removing  inlays:  Take  a  German 
silver  wire  and  flatten  the  end  with  a  hammer;  now  trim  ofif  the  edges  until  the  flat 
part  is  only  as  wide  as  the  thickness  of  the  wire;  now  hold  the  wire  in  your  pin  vise, 
catching  close  to  the  flat  part,  and  with  a  pair  of  pliers  twist  the  flat  part  to  form  a 
screw,  point  the  end  with  a  file  and  you  have  a  sprue  wire  that  will  hold. 

Do  not  warm  the  wire,  but  insert  by  a  pushing  twist,  thus  screwing  the  sprue 
into  the  impression.  Blow  a  stream  of  cold  air  on  the  impression  and  your  wire  will 
hold. 


CAST  BACKINGS  AND  CROWNS  FOR  STEELE'S  FACINGS 

By  James  B.  Doyle,  D.D.S.,  Grand  Rapids,  Mich. 

First  take  the  Steele  facing,  then  a  piece  of  platinum  or  pure  gold,  about  36- 
gauge.  Pinch  it  together  and  insert  it  in  the  groove,  then  take  a  small  instrument 
and  burnish  it  to  place  so  that  it  fits  the  groove  perfectly,  then  take  a  piece  of  22k 
plate  gold  or  platinum  and  cut  it  so  it  will  readily  pass  into  the  root  canal  and  the 
groove  of  the  facing.  Remove  and  solder  these  two  pieces  together;  after  greasing 
your  facing  with  vaseline  you  are  ready  for  your  inlay  wax.  Mold  it  as  well  as 
possible  to  the  back  of  the  facing  and  your  root  canal  pin.  Then  after  the  wax  is 
properly  warm  you  insert  it  in  the  root  canal  and  press  up  firmly.  Remove  and 
carve  until  you  have  the  shape  desired.  Then  remove  your  facing  and  you  are 
ready  for  casting.  Now  you  have  a  perfect  fit  of  your  facing  to  your  backing  and  a 
perfect  fit  to  your  canal. 

I  cast  all  my  backings  for  Steele's  facings.  You  proceed  in  the  same  manner 
except  that  you  do  not  use  a  pin.  There  is  a  great  advantage  in  making  bridges 
with  Steele's  facings  and  casting  your  backings.  The  reason  so  many  facings  break 
is  because  you  cannot  get  uniform  thickness  with  solder.  You  will  get  a  little  more 
solder  in  one  place  than  another  and  it  is  liable  to  spring.  That  spring  will  be  just 
enough  to  crack  your  facing.  And  another  thing,  you  cannot  always  get  your 
backings  to  fit  so  that  the  stress  of  mastication  will  come  upon  it.  By  casting  vour 
backings  you  overcome  these  difficulties. 


CAST  CUSP  CROWN 

By  C.  E.  White,  Indianapolis,  Ind. 

Prepare  root  in  proper  manner,  cut  a  piece  of  22k  gold  large  enough  to  make  the 
band,  wide  enough  to  include  cusps,  fit  the  band  to  root  and  trim  to  occlusion. 
Contour  the  band  with  pliers  to  form  the  cusps.  Place  warm  inlay  wax,  or  better 
still,  Alexander's  gold,  inside  the  band,  condense  same  or  trim  and  carve  (if  wax) 
to  occlusion.  If  wax,  invest  and  cast;  if  Alexander's  gold,  place  solder  on  cusp  of 
crown,  place  over  Bunsen  burner,  burn  out  wax  and  sweat  solder  in  the  gold.  Polish 
the  crown  and  cement  it  on  at  the  same  sitting. 


AN  INLAY  FOR  COMPOUND  CAVITY  INVOLVING  INCISAL 
V^ITHOUT  STEP 

By  H.  C.  Dean,  D.D.S.,  Columbus,  Ohio. 

It  is  often  desired  to  place  a  gold  inlay  involving  the  approximal  side  and  incisal 
edge,  without  sacrificing  the  sound  structure  of  the  tooth  to  make  a  step.  This  may 
be  done  by  placing  an  iridio-platinum  post  near  the  incisal  after  the  inlay  has  been 
completed.  Inlay  should  have  a  wide,  deep  groove  carved  in  the  approximal  surface 
extending  from  near  the  incisal  to  the  gingival.  This  should  be  done  in  the  wax 
model.  This  groove  is  to  pass  over  the  iridio-platinum  post,  when  the  inlay  may  be 
set  from  the  incisal  without  interference  from  an  approximating  tooth.  There  may 
be  an  extension  of  this  iridio-platinum  post  for  additional  retention  in  the  groove  of 
the  inlay.  Since  the  inlay  model  is  completed  before  the  incisal  retention  post  is 
provided,  there  is  absolutely  no  interference  with  the  removal  of  the  model.  The 
retention  post  fits  loosely  in  the  tooth  and  in  the  inlay  until  cemented.  Post  and 
inlay  are  both  set  with  same  mix  of  cement. 


HOW  TO  CAST  AN  INLAY  WHEN  YOUR  CASTING  MACHINE  IS 
OUT  OF  ORDER 

By  Dr.  W.  J.  Boydston,  Fairmont,  W.  Va. 

The  casting  machine  consists  of  a  tube  alxnit  eight  inches  long  and  about  an 
inch  and  a  half  in  diameter,  filled  with  plaster  of  Paris  to  within  about  two  inches  of 
the  top.  Fill  this  vacancy  with  putty  or  moldine.  Over  this  place  wet  tissue  paper, 
about  six  to  eight  thicknesses.  Heat  your  investment  and  proceed  as  in  other  cast- 
ing, exerting  about  six  to  eight  pounds  of  hand  pressure. 

Then  this  other  crown  is  a  porcelain-faced  cap  crown,  by  use  of  Steele  facing  with 
cast  back.  You  grind  your  tooth  the  same  as  for  a  gold  crown;  then  grind  buccal 
surface  the  same  as  for  Richmond  crown.  Then  cut  face  of  band  out;  swage  your 
cusp  and  catch  it  on  the  lingual  edge  of  band  with  solder;  readjust  to  tooth;  allow 
patient  to  bite  and  adjust  articulation.  Then  grind  Steele  facing  to  approximately 
fit  portion  of  band  ground  away;  cut  back  the  facing  with  vaseline;  press  it  into 
warm  casting  wax  and  while  still  warm  place  on  face  of  band.  Press  into  place, 
chili,  remove,  trim,  and  build  up  contour  with  wax.  Remove  facing,  insert  screw 
in  the  buccal  incisor  edge  of  wax;  invest,  and  proceed  as  in  other  casting.  After 
casting  flow  solder  around  cast  and  band.     Grind  down  and  finish  and  place  in  facing. 


TABLE  OF  CONTENTS 

The  Cast  Inlay: 

Early  Attempts  at  Inlay  Casting C.  V.  Vignes 12 

Tcchnic  of  a  Cast  Gold  Inlay A.  F.  Miller 13 

Cavity  Preparation  for  Cast  Gold  Inlay Thomas  P.  Hinman.  37 

Shaping  Wax  Model  for  Gold  Inlays C.  E.  Abbott 38 

The  Cement  Line  in  Inlays Clarence  J.  Grieves.  39 

Some  Practical  Points  on  Inlays L.  E  Custer 68 

Separate  Base  for  Gold  Inlay F.  R.  Henshaw 67 

The  Cast  Gold  Inlay James  W.  Lyons ...  81 

Anchor  for  Fillings  and  Inlays W.  H.  Pelton 105 

Method  of  Producing  Perfect  Margins C.  Kabell 116 

Nuggets  of  Gold — Inlays O.  E.  Lanphear.  ...  117 

Limitations  and  Uses  of  the  Gold  Ink}- H.  M.  Semans 120 

The  Gold  Inlay J.  V.  Conzett 122 

Hollow  Cast  Inlays W.  S.  Payson 125 

To  Hollow  Out  Wax  Model  for  Inlay S.  T.  Neill 125 

Casting  Wax T.  C.  Trigger 136 

The  Impression  Method  for  Inlay  Work Henry  W.  Gillett.  .  .  137 

The  Cast  Gold  Inlay C.  G.  Myers 149 

Porcelain  and  Gold  Inlays A.  W.  Starbuck.  .  .  .  163 

Amalgam  Base  for  Gold  Inlay Steele  F.  Gilmore ...  192 

The  Working  Model  for  Inlay  Practice H.  W.  Arthur 205 

Conductivity  of  Cast  Inlays S.  H. Guilford 208 

Some  More  Progression R.  C.  Brophy 213 

Inlay  Casting  by  the  Vacuum  Process L.  W.  Strycker   .  .  .  230 

Holding  Inlays  While  Polishing G.  B.  Speer 245 

Combination  Fillings  of  Cast  Gold  and  Porcelain  on 

Silicate  Cement C.  H.  Neill 239 

Inlay  for  Compound  Cavity H.  C.  Dean 246 

How  to  Cast  an  Inlay  When  Casting  Machine  is  Out 

of  Order W.  J.  Boydston 246 

Crown  and  Bkidgk  Work: 

Porcelain  Crown  with  Cast  Gold  Base W.  .\.  Sanderson    .  .  14 

Telescopic  Crown  for  Bridge  Work E.  L.  Kanaga 22 

Casting  Process  as  Applied  to  Crown  and  Bridge  Work .  Hart  J.  Goslce 28 

Restoring  Teeth  for  Crown  and  Bridge  Work C.  Jensen 67 

Hollow  Wax  Dummies  of  Bicuspids  and  Molars T.  C.  Hutchinson..  .  69 

Cast  Gold  Crown C.  E.  Mcerhoff 80 

Cast  Jointed  Logan  Crown C.J.  Burris 80 

Casting  Pins  for  Crowns W.  A.  Stewart 102 

Casting  Backings  for  All-Porcelain  Fronts D.  Haight 102 

Anterior  Bridge  Abutments  for  Splinting George  C.  McCann.  104 

Cast  Posts  for  Steele's  Facings George  H.  Walker.  .  106 

Methods  of  Casting  in  Crown  and  Bridge  Work W.  G.  Crantlall       .  .  107 

An  Ideal  Bicuspid  or  Molar  Crown George  S.  Schlegel.  .  Ill 

Cast  Abutments  for  Bridges W.  W.  McCall 112 

Pin  and  Coping  for  Porcelain  Crown Paul  J.  l>o\cns 115 


TABLE  OF  CONTENTS— Continued 

Crown  and  Bridge  Work J.  H.  Laudry 123 

An  Anterior  Cast  Bridge E.  Cunningham  ....    125 

Casting  Large  Bridges W.  H.  Hayden 126 

A  Richmond  Crown  Without  Solder T.  C.  Hutchinson. .  .    127 

To  Overcome  Weakness  of  Cast  Gold  Bridge W.  J.  Montgomery.    136 

A  Combination  Cast  Crown O.  H.  Simpson 155 

Restoration  by  All-Porcelain  Bridge  and  Bridges  upon 

Cast  Bases J-  M.  Thompson  .  .  .    157 

Subgingival  and  Canal  Restoration  in  Crown  Work..  .Edward  C.  Mills,  .  .    161 

Casting  on  Porcelain W.  C.  Gillespie 217 

Cast  Backings  and  Crowns  for  Steele's  Facings James  B.  Bayle 245 

Reinforcing  Principle  of  Mesh  in  Wax  Pattern  Work.  .A.  W.  Gatham 234 

The  Technique  of  Casting C.  E.  Talbert 240 

Cast  Cusp  Crown C.  E.  White 246 

Root  Restorations: 

Restoring  Bicuspid  Roots Auber  Peebles 18 

Restoration  of  Fractured  Root J.  Maurice  Crosby. .  64 

Restoration  of  Broken- Down  Roots  with  Acolite James  B.  Lester.  .  .  .  103 

Restoration  of  Roots  of  Bicuspids  and  Molars A.  W.  McCullough..  160 

Cast  Metal  Plates: 

Preparing  Inlay  Wax  for  Base  Plate Newton  W.  Hiatt. .  .      68 

The  Cast  Aluminum  Plate Robert  Se^'mour.  .  . .   133 

Collodion  as  a  Separating  Medium B.  L.  Worthley 136 

Cowbell  Method  of  Casting  Plates D.  D.  Campbell 197 

Cast  Aluminum  Plates George  H.  Wilson. . .   200 

To  Obtain  a  Smooth,  Dense  Surface  on  Casts F.  L.  Olds 215 

Plate  Casting  by  the  Vacuum  Process W.  L.  Harpel  and 

F.  L.  Olds 225 

Origin  and  Progress  of  Dental  Casting: 

Ancient  Origin  of  Dental  Casting L.  W.  Stryckcr 5 

Experience  and  Experiments  in  Casting. J-  R-  Osborne 65 

Latest  Developments  in  the  Cast  Gold  Process Albert  L.  LeGro.  ...      71 

Casting;   A  Retrospect J-  G.  Lane 91 

The  Scope  of  Casting  in  Dentistry R.  C.  Brophy 113 

Gleanings  from  the  Field  of  Experience: 

Investing  to  Avoid  Shrinkage  and  Distortion C.  J.  Clark 15 

Expansion  and  Contraction  of  Gold  in  Casting C.  J.  Clark 19 

Air  Vents  in  Casting D.  D.  Smith 68 

A  Soldering  Device T.  B.  MaGill 90 

Casting  Gold  on  Porcelain E.  Cunningham  ....  122 

The  Cast  Clasp W.  B.  Caldwell.  .116-132 

Places  Where  the  Casting  Process  Has  Been  Found 

Useful E.  T.  Tinker 193 

Cast  Gold  Splints  for  Pyorrhea J.  G.  Lane 196 

Some  Pha.ses  of  the  Casting  Process C.  S.  Van  Horn  ....  202 

Reproduction  of  Flowers,  Etc.,  by  Casting T.  C.  Hutchinson..  .  210 

Remarks  on  Casting Robert  N.  LcCron. .  221 


ANOTHER    VALUABLE    BOOK 

Interstitial  Gingivitis 

and 

Pyorrhoea  Alveolaris 


By  EUGENE  S.  TALBOT,  M.  S.,  D.  D.  S.,  M.  D.,  LL.  D. 

Late  Professor  of  Stomatology,  Woman's  Medical  School,  Northwestern 
University;  Late  Lecturer  on  Stomatology,  Rush  Medical  College,  University  of 
Chicago;  Fellow  of  The  Chicago  Academy  of  Medicine;  Fellowship  Member  of  the 
New  York  State  Dental  Society,  1908;  Secretary  of  Section  on  Stomatology  of  the 
American  Medical  Association;  Vice-President  American  Medical  Association,  1905; 
Member  VII  International  Medical  Congress,  1881,  London;  Honorary'  President  X 
International  Medical  Congress,  1890,  Berlin;  Honorary  President  XII  International 
Medical  Congress,  1897,  Moscow;  Corresponding  Member  Budapest  Royal  Society 
of  Physicians;  Honorary  President  International  Association  of  Stomatology,  1907, 
Paris;  Member  First  French  Congress  of  Stomatology,  1907,  Paris;  Honorary 
Secretary  Pan-American  Medical  Congress,  1901,  Havana;  Honorary  Member 
Odontologischen  Gesellschaft,  Berlin;  Honorary  Member  Association  Generale  des 
Dentistes  de  France,  Paris;  Honorary  Member  Sociedad  Odontological  Espanola, 
Madrid;  Corresponding  Member  Dansk-Tandlaegeforening,  1901;  Honorary 
Member  Stomatology  Society  of  Hungary;  Corresponding  Member  of  the  Italian 
Stomatological  Federation,  1910;  Member  Chicago  Academy  of  Sciences;  Member 
American  Association  for  the  Advancement  of  Science;  Charter  Member  American 
Institute  of  Criminal  Law  and  Criminology;  Member  of  the  Authors'  Club,  London. 
Author  of  the  following  books:  "The  Irregularities  of  the  Teeth  and  Their  Treat- 
ment;" "Chart  of  Typical  Forms  of  Constitutional  Irregularities  of  the  Teeth;" 
"The  Etiology  of  Osseous  Deformities  of  the  Head,  Face,  Jaws  and  Teeth;"  "De- 
generacy: Its  Signs,  Causes  and  Results;"  "Developmental  Pathology:  A  Study  in 
Degenerative  Evolution,"  Etc.,  Etc. 

PARTIAL  CONTENTS 

Transitory  Structures::  The  Jaws  and  Alveolar  Process;  The  Alveolar  Process 
Under  the  Microscope;  The  Gums,  Periosteum,  Mucous  and  Peridental  Membranes 
Under  the  Microscope;  Inorganic  Salts  and  Interstitial  Gingivitis;  Theories  of 
Interstitial  Gingivitis;  Degenerate  Acid  and  Interstitial  Gingivitis;  Heredity  and 
Environment  in  Interstitial  Gingivitis;  Degenerate  Tissues  in  Interstitial  Gingivitis; 
Bacteriologic  Researches  in  Interstitial  Gingivitis;  Interstitial  Gingivitis;  Researches 
on  Animals  in  Interstitial  Gingivitis;  Researches  on  Human  in  Interstitial  Gingivitis; 
Researches  on  Human  in  Pericementis;  Local  Causes  of  Interstitial  Gingivitis;  Consti- 
tutional Causes  of  Interstitial  Gingivitis;  Climate  Influences  in  Interstitial  Gingivitis; 
Scurvy  in  Interstitial  Gingivitis;  Toxins  Producing  Trophic  Changes;  Autointoxica- 
tion in  Interstitial  Gingivitis;  Urinary  Signs  of  Autointoxication;  Arteriosclerosis, 
Endareritis  Obliterans  and  Nerve  End  Degeneration;  Absorption  of  the  Alveolar 
Process  and  Calcic  Deposits  upon  the  Roots  of  the  Teeth;  Pyorrhea  Alveolaris; 
Constitutional  Effects  of  Pyorrhea  x^lveolaris;   Treatment. 

See  reviews  and  opinions  of  this  book  on  next  page. 

335  Pages     :     CLOTH  $4.40     :     102  Illustrations 
Published  by  The  Ransom  &  Randolph  Co.,  Toledo,  Ohio 


Dr.  James  Truman,  in  an  exhaustive  review  of  more  than  six  pages,  in  The  Dental 
Brief  {or  July,  1913,  says: 

A  new  work  from  the  pen  of  Dr.  Talbot  is  an  event  not  to  be  passed  as  a  mere 
trifle  on  the  great  ocean  of  professional  literature,  but  as  a  pronounced  advance  in 
scientific  knowledge.  It  seems  only  yesterday  that  a  work  from  this  indefatigable 
investigator  and  writer  was  published,  that  the  present  writer  regarded  then  as  the 
author's  masterpiece,  but  before  the  ink  is  scarcely  dry  in  this  comes  this  volume  on 
interstitial  gingivitis,  the  last,  it  is  presumed,  that  will  appear  in  book  form  from  the 
author's  pen. 

Dr.  Talbot's  work  is  always,  to  the  inquiring  student,  a  mine  of  facts.  He  does 
not  deal  in  theories,  and  the  worker  in  his  mine  must  be  prepared  with  pick  and 
shovel  to  delve  with  him  deeply  in  the  strata  of  undiscovered  things. 

This  work  is  beyond  question  the  only  thorough  exposition  of  this  pathological 
condition  familiar  to  the  reviewer,  either  in  Europe  or  America. 

That  there  is  no  specific  germ  capable  of  producing  this  disease  is  abundantly 
shown,  as  the  work  proceeds,  and  the  researches  of  Galippe  have  not  been  confirmed, 
either  by  the  author  or  those  associated  with  him.  Dr.  Theodore  Chapin  Beebe* 
in  a  valuable  article  on"  Pyorrhea  Alveolaris  and  Treatment  by  the  Opsonic  Method," 
says  our  vaccines  are  standardized  at  staphylococci  3^  c.c.  equalling  500  million, 
pneumococci  ]/>  c.c.  equalling  100  million.  These  are  mentioned  as  being  the  two 
most  common  bacteria  found  in  inflammatory  conditions  of  the  gums. 

Chapter  IX  is  taken  up  with  the  question  of  uric  acid,  which  so  largely  dom- 
inated the  dental  profession  at  one  period,  especially  by  Peirce,  Rhein  and  others. 
The  judgment  of  the  former  was  based  on  several  experiments  conducted  at  the 
Drexel  Institute,  Philadelphia.  The  author  claims  that  these  were  too  limited  in 
number  to  be  regarded  as  conclusive.  He,  the  author,  had  had  altogether  "nine 
hundred  and  fifty  cases,  and  only  a  fourth  per  cent,  showed  uric  acid  *  *  *  j^ 
It  is  safe  to  say  that  six  per  cent,  was  the  actual  per  cent,  of  uric  acid." 

In  the  chapter  on  "Heredity  and  Environment,"  the  author  sums  up  his  con- 
clusions in  a  few  words,  "Interstitial  gingivitis  and  pyorrhea  alveolaris  are  not 
inherited." 

Chapter  XVII  is  one  every  dentist  should  carefully  study.  It  is  devoted  to 
"Local  Causes  of  Interstitial  Gingivitis."  If  there  was  nothing  more  than  this 
sentence  in  it,  it  should  cause  the  average  operator  to  think  before  deciding  to  operate 
on  a  patient.  "  In  a  word,  whatever  irritates  the  gum  margin,  peridental  membrane, 
or  alveolar  process,  is  likely  to  produce  inflammation  which  later  becomes  chronic." 
Nothing  more  suggestive  could  be  framed  in  words.  The  author  might  have  ex- 
tended this  chapter  in  the  direction  of  warnings,  and  while  he  covers  much,  there  is 
still  more  to  be  written  on  errors  in  crownwork,  bridgework,  etc. 

In  the  chapter  on  "Absorption  of  the  Alveolar  Process  and  Calcic  Deposits," 
the  author  states  that  interstitial  gingivitis  extends  to  the  alveolar  process  through 
the  periosteum  as  well  as  through  the  peridental  membrane,  and  not  (as  dentists 
usually  believe)  by  way  of  the  peridental  membrane  alone. 

The  reviewer  rises  from  the  reading  of  this  book  of  Dr.  Talbot  with  a  high  appre- 
ciation of  its  contents.  He  feels  assured  that  any  one  essaying  to  treat. interstitial 
gingivitis,  or  pyorrhea  alveolaris,  will  be  better  able  to  effect  results,  let  his  method 
be  what  it  may,  or  however  skilled  he  may  be  through  experience.  No  other  work 
with  which  the  writer  is  acquainted  can  compare  with  this  in  a  clear  elucidation  of 
the  various  phases  of  this  important  oral  pathological  condition.  It  covers  all 
possibilities,  but  it  will  demand  serious  study.  To  buy  this  book  and  place  it  on  the 
library  shelf  for  occasional  reference  will  not  answer  the  author's  purpose,  nor  does  it 
appeal  to  the  present  writer.  The  work  deals  with  a  scientific  problem,  and  problems 
of  this  nature  require  mental  devotion  of  no  ordinary  character  for  their  solution. 
The  ideas  sought  to  be  taught  must  be  made  the  operator's  own.  He  must  learn  to 
think  in  the  language  of  the  science  taught,  and  then  diagnoses  become  a  part  of  his 
secondary  nature.  In  the  final  analysis  the  writer  holds  that  the  pathological  con- 
ditions of  the  oral  cavity  and  its  relations  to  the  general  system  will  and  must  be 
conquered  by  stomatologists,  and  this  accomplished,  the  health  of  the  world  will  be 
placed  on  a  much  higher  plane  than  has  ever  previously  been  known. 

James  Truman. 

'*Dental  Cosmos  for  May,  1913. 


From  The  Dental  Digest,  August,  1913; 

In  this  new  work  from  the  pen  of  Dr.  Talbot  we  have  the  sum  and  suljslance  ot 
an  experience  covering  thirty-five  years  spent  in  honest,  intelligent  and  conscientious 
research  study  on  the  subject  of  the  etiology,  pathology  and  treatment  of  peridontal 
disease.  The  etiological  experiments  and  treatment  are  made  from  the  viewpoint 
that  disease  of  the  gums  ancl  the  alveolar  process  are  of  an  infectious  nature;  but  as 
many  different  tissues  and  organs  of  the  body  undergo  physiological  and  chemical 
changes,  often  due  to  inflammation  from  irritating  causes,  the  author  has  endeavored 
to  separate  or  classify  those  inflammations  due  to  infections,  and  those  due  to 
chemical  and  local  changes  and  constitutional  irritations. 

Dr.  Talbot,  in  his  introduction  to  this  most  valuable  book,  says:  "The  attempt 
has  been  made  in  the  present  work  to  reduce  to  order  the  chaotic  notions  as  to 
etiology,  pathology  and  treatment  which,  during  the  present  century,  have  gathered 
around  the  morbid  conditions  erroneously  entitled  Pyorrhea  Alveolaris.  While 
even  erroneous  titles  may  have  their  meaning  so  fixed  by  usage  that  any  danger 
from  the  error  involved  in  the  title  may  be  practically  nil,  still  this  is  not  the  case 
with  the  title  just  cited.  It  suggests  erroneous  etiology,  since  pyorrhea  implies  that 
there  must  always  be  a  flow  of  pus,  and  hence  that  the  disease  must  always  result 
from  infection  with  pus  microbes.  It  implies  erroneous  pathology  and  erroneous 
treatment  for  the  same  reason.  This  being  the  case,  such  a  title  is  so  dangerously 
misleading  as  to  compel  in  the  present  stage  of  dental  science  its  modified  use  as  a 
term  for  disease.  With  a  view  of  clearing  up  this  question  at  the  outset  by  the  use  of 
a  proper  title,  I  have  adopted  as  a  designation  for  the  condition  hitherto  known  as 
pyorrhea  alveolaris  the  term  'Interstitial  Gingivitis'." 

He  considers  the  term  interstitial  is  used  by  some  pathologists  in  a  .limited, 
obscure  sense,  but  by  the  mass  of  dental  pathologists,  surgeons,  physicians,  and  by 
medical  lexicographers,  the  term  is  employed  in  precisely  the  sense  in  which  it  is 
used  in  the  present  work,  and  he  quotes  in  support  of  his  assertion  the  English 
surgeon  and  lexicographer,  Quain,  and  Foster's  "Encyclopaedic  Medical  Dictionary" 
(American). 

One  should  closely  read  the  introduction  and  thoroughly  digest  it,  for  it  most 
fully  describes  the  work  which  the  author  so  ably  presents  to  his  brothers  of  the 
dental  profession. 

A  glance  at  the  chapter  heads  will  give  the  reader  some  idea  of  the  scope  of  the 
book: 

Chapter  V  is  of  especial  interest;  it  is  confined  principally  to  the  histological 
appearance  of  The  Alveolar  Process  Under  the  Microscope.  Chapter  VHI  deals 
with  Theories  of  Interstitial  Gingivitis.  Perhaps  the  most  interesting  chapter  is 
XII — Bacteriologic  Researches  in  Interstitial  Gingivitis.  A  number  of  extremely 
interesting  experiments  are  reported,  and  from  these  reported  experiments  Dr. 
Talbot  forms  the  conclusion  that  "outside  of  a  few  specific  diseases  of  the  gums  and 
alveolar  process,  some  of  which  have  been  enumerated,  no  one  has  demonstrated 
that  specific  pathogenic  bacterial  infection  is  a  cause  of  interstitial  gingivitis,  al- 
though the  mouth  is  known  to  be  the  breeding  ground  of  an  extensive  variety  of 
germs." 

Chapter  XVII  is  devoted  to  "Local  Causes  of  Interstitial  Gingivitis."  The 
close  reading  by  dentist  and  student  is  recommended  for  this  chapter;  indeed,  it 
would  b;-  difficult  to  mention  any  chapter  that  would  not  be  good  and  instructive 
reading. 

The  illustrations  are  excellent,  each  one  being  well  described.  There  is  also  an 
index,  that  indispensable  appendix  to  any  book  of  reference.  The  book  is  printed 
on  excellent  paper  in  good  readable  type,  and  well  bound.     We  wish  it  success. 


fi„i  rlate  indicated  below,  oi 
This  book  is  due  on  the  date  m  ^^  borrowing,  as 

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